Learn How To Size Up A Sewing Pattern For Perfect Fit

Yes, you absolutely can size up a sewing pattern! This article will show you how to make a sewing pattern bigger so you can get a great fit for your body. We will cover taking accurate measurements, figuring out pattern sizes, and using smart methods to change the pattern pieces.

Sewing patterns are a starting point. They are not made just for you. Your body has its own shape. It has its own measurements. A store-bought pattern might be too small in one spot. It might be too small all over. When you learn to make pattern adjustments, you make the clothes fit you. Sizing up a sewing pattern is a key skill. It helps you sew clothes that feel good and look good. It is about making the garment pattern fit your unique shape.

How To Size Up A Sewing Pattern
Image Source: mellysews.com

Why Make a Pattern Bigger?

Patterns come in sizes. But bodies do not always fit neatly into those sizes. Maybe your chest is larger than the size chart says. Maybe your hips are wider. Maybe you are just a bit larger than the biggest size in the pattern pack.

Patterns use standard measurements. These are based on averages.
Your body is not average. It is special.
A pattern in your size might fit one part of you. But another part might be too tight.
Making the pattern bigger lets you add room exactly where you need it.
This means your finished garment will be comfortable. It will move with you.

Learning how to size up means you are not limited by the sizes on the pattern envelope. You can sew more styles. You can sew more projects. It gives you freedom in your sewing. It is a big step in fitting pattern to body.

Getting Ready to Change Your Pattern

Before you start changing anything, you need a few things. Gather your tools. Get your workspace ready.

Your sewing pattern: Make sure it is the correct view or style you want to make.
Measuring tape: A flexible cloth or plastic one is best for bodies.
Paper for pattern work: This is important. Do not cut your original pattern piece right away if you can help it. Use pattern paper, tissue paper, or even tracing paper. Some people use Swedish tracing paper because you can sew it.
Clear ruler: A see-through ruler helps you draw lines. A curved ruler is great for blending lines later.
Pencil, pen, or marker: Use something that shows up well on your paper.
Tape: Standard clear tape works well. Special pattern tracing tape is also an option.
Paper scissors: Use scissors just for paper. Fabric scissors will get dull if you cut paper.
Seam ripper: Just in case! (Not for the pattern, but for sewing later).

Have a clear, flat surface to work on. Spread out your pattern pieces. Take your time. This is a step-by-step process.

Taking Accurate Body Measurements

This is the most important step. You cannot change a pattern to fit you if you do not know your own measurements. Taking body measurements for sewing is different from measuring for store clothes. You need specific measurements.

Wear the kind of underwear you will wear with the finished garment. A good bra is key for bust measurements.
Stand up straight. Do not hold your breath or suck in your stomach. Be natural.
Ask a friend for help if you can. It is much easier to measure someone else than yourself. Especially for the back and hip areas.
Keep the tape measure level all the way around your body. Use a mirror to check the back.
Do not pull the tape measure too tight. Do not let it sag. It should feel snug, but you should be able to put a finger between the tape and your body.

Here are the key measurements you need. Measure these points. Write them down right away.

Key Body Measurements

h5 Bust Measurement
* Measure around the fullest part of your bust.
* Keep the tape level across your back and around the front.
* This is often needed for bodice patterns.

h5 High Bust Measurement
* Measure around your chest, right under your arms, and above your bust.
* This helps figure out your cup size relative to the pattern’s design. It is very useful for fitting the top of the bodice.

h5 Waist Measurement
* Find your natural waist. This is usually the narrowest part of your torso. It is often just above your belly button.
* Bend to the side. The crease is your waist.
* Measure around your natural waist.

h5 Hip Measurement
* Measure around the fullest part of your hips and bottom.
* This is usually about 7-9 inches (18-23 cm) below your natural waist.
* Keep the tape level all the way around.

h5 Back Width Measurement
* Measure across your upper back. Go from where one arm joins your body to where the other arm joins your body. Measure about 4 inches (10 cm) down from the base of your neck.

h5 Shoulder Width Measurement
* Measure from the tip of one shoulder to the tip of the other shoulder. Find the bony point at the top edge of your shoulder.

h5 Arm Length Measurement
* Bend your arm slightly.
* Measure from the top of your shoulder point, down past your elbow, to your wrist bone.

h5 Bicep Measurement
* Measure around the fullest part of your upper arm.
* Do this with your arm relaxed.

h5 Thigh Measurement
* Measure around the fullest part of one thigh.
* Do this right at the top of your leg, up near your crotch.

h5 Inseam Measurement
* For pants or shorts.
* Measure from the point where your legs meet at the crotch down to where you want the hem to end. It is best to measure a pair of pants that fit you well for this. Lay them flat and measure along the inseam.

Record Your Measurements

Use a table like this to keep track of your numbers. This is your personal sewing pattern measurements guide.

Measurement	Your Measurement (Inches or CM)
Bust
High Bust
Waist
Hip
Back Width
Shoulder Width
Arm Length
Bicep
Thigh
Inseam
Add others you need

Keep this list handy. You will use it often.

Interpreting Pattern Sizing

Now you have your body numbers. Look at the pattern envelope. Find the size chart. This chart lists body measurements. It tells you which pattern size matches those body measurements.

Look at the measurements for the pattern sizes listed.
Find the size that is closest to your bust measurement. This is often the size suggested by pattern companies for tops and dresses.
Find the size that is closest to your hip measurement. This is often the size suggested for skirts and pants.
If your bust measurement puts you in size 12, but your hip measurement puts you in size 16, you know you will need to make changes. You will likely start with the size 12 pattern pieces for the top. Then you will need to make the hip area larger to fit your size 16 hip number.

Pattern sizes are not standard across companies. A size 14 from Company A might be different from a size 14 from Company B. Always use the measurements on the chart, not just the size number.

Grasping Ease in Patterns

This part is important. Patterns include “ease.” Ease is the extra room in the garment.

Wearing Ease: This is the minimum amount of extra room you need to move, sit, and breathe. A close-fitting dress needs less wearing ease than a loose jacket.
Design Ease: This is extra room the designer added to create the look of the garment. A flowy top has a lot of design ease. A tight pencil skirt has very little.

The pattern measurements on the envelope often show the body measurements the size is meant to fit. The finished garment measurements (often printed on the pattern pieces themselves or in the instructions) include the ease.

Compare your body measurements to the pattern’s body measurement chart.
Figure out the difference. This difference is how much you need to add to the pattern pieces.
Remember that the pattern pieces are usually half or a quarter of the total needed amount (because fabric is cut on the fold or you cut two pieces). If you need to add 2 inches to your total hip measurement, you will add 1 inch to the back hip piece and 1 inch to the front hip piece (assuming you have two pieces each, which is common). Or 0.5 inches to each quarter piece if cut on fold. Divide the total amount needed by the number of pattern pieces covering that area.

Let’s say your bust is 40 inches. The pattern size chart says size 14 fits a 36-inch bust. You need to add 4 inches to the pattern’s bust measurement in total. If the pattern has a front bodice piece and a back bodice piece, and both are cut once on the fold, you have two halves. You need to add 2 inches to the front bodice width and 2 inches to the back bodice width at the bust line. You will spread this amount across the piece.

Methods for Enlarging Sewing Patterns

There are several ways to make a pattern bigger. The best method depends on how much size you need to add and where you need to add it. These are all types of pattern alteration techniques and methods for resizing garment patterns.

The Slash and Spread Method

This is a very common technique for sewing pattern adjustments. It is great for adding size to specific areas like the bust, waist, or hips, or to add length.

Concept: You cut the pattern piece along certain lines (slash). Then you move the cut pieces apart (spread). This creates a gap. You fill this gap with extra paper.
Why it works: It adds size smoothly across the area, keeping the original shape of the pattern piece lines.

Here are steps for using slash and spread on common pattern pieces. You will need your pattern paper, ruler, pencil, and tape.

Enlarging Bodice Pieces with Slash and Spread

Bodices are often the trickiest. You might need to add to the bust, waist, or hip area. You might also need a Full Bust Adjustment (FBA). An FBA adds room specifically for the bust without adding too much width everywhere else.

h5 Steps for a Simple Bust/Waist/Hip Slash and Spread (If adding width across the whole piece)

Trace the pattern piece: Always trace your original pattern piece onto fresh paper first. This way, if you make a mistake, you can start over. It also saves your multi-size pattern.
Draw vertical lines: Draw one or more vertical lines on the pattern piece. These lines should go from the hem or lower edge up towards the armhole or shoulder. A common place is straight up from the waistline towards the armhole. Draw another line from the waist down to the hip if needed.
Draw a horizontal line: Draw a horizontal line across the pattern piece where you need the most width added (e.g., at the bust line or hip line).
Slash the lines: Cut carefully along the vertical lines you drew, stopping just before you reach the edge of the pattern or a seam line. Leave a small “hinge” of paper so the pieces do not separate completely. If cutting a horizontal line, slash from the side seam towards the center, again leaving a hinge. For some adjustments like an FBA, you’ll slash more complex lines including through a dart.
Spread the pieces: Gently pull the cut sections apart. Spread them the amount you need to add to that section. Remember, if you need to add 2 inches total to the bust, and you are altering the front bodice piece which is cut on the fold (a half piece), you might spread the vertical slash by 1 inch (since 1 inch spread x 2 halves = 2 inches total added).
Place paper underneath: Slide a piece of fresh pattern paper under the gap you created.
Tape in place: Tape the pattern piece sections onto the new paper, keeping the gap the correct size all the way down the slash line.
Draw new lines: Draw new, smooth lines to connect the edges of the altered piece. This is called “truing” the lines. Blend the side seams, hem, and armscye (armhole) lines smoothly. Use your curved ruler here.
Adjust related pieces: If you changed the bodice side seam, you might need to make a matching change on the skirt or pant piece that attaches there. If you changed the armscye, you might need to adjust the sleeve piece.

Enlarging Sleeves with Slash and Spread

Adding width to a sleeve, especially at the bicep, is common.

h5 Steps for Sleeve Adjustment

Trace the sleeve pattern piece.
Draw a vertical line: Draw a line down the center of the sleeve pattern piece, from the top (sleeve cap) to the hem.
Draw a horizontal line: Draw a horizontal line across the sleeve where you need to add width, usually at the bicep level or a bit lower.
Slash the vertical line: Cut the vertical line from the hem up to the horizontal line. Cut along the horizontal line from the vertical slash out to the side seam, again leaving hinges.
Spread: Spread the vertical slash the amount needed to add width to the bicep (remembering this is a half-sleeve piece usually, so spread half the total amount needed). Spreading the horizontal slashes will add extra room at the bicep line.
Tape in place: Tape onto new paper.
Draw new lines: Redraw the sleeve cap curve and side seams smoothly. The hem might need a slight adjustment too.

Enlarging Skirts and Pants with Slash and Spread

You might need to add width at the waist, hip, or thigh.

h5 Steps for Skirt/Pants Adjustment

Trace the pattern piece.
Draw vertical lines: Draw one or more vertical lines from the hem up to the waistline. For pants, you might draw one line up the center of the leg and one or two more between the center and the side/inseam.
Draw horizontal lines: Draw horizontal lines at the hip level, perhaps the thigh level, and maybe the knee level.
Slash: Cut along the vertical lines, stopping at the horizontal lines or the waist/hem. Cut along the horizontal lines from the vertical slashes out to the side seams or inseams, leaving hinges.
Spread: Spread the pieces apart vertically the amount needed at each horizontal line (waist, hip, thigh). Spread them evenly. If you only need extra room at the hips, you only need to spread the cuts around the hip line. If you need extra room through the whole leg, spread the cuts down the length.
Tape in place: Tape onto new paper.
Draw new lines: Smooth out the side seams, inseams, crotch curve, and waistline. Be especially careful with the crotch curve on pants – small changes here make a big difference in fit.

Grading Between Sizes

Many patterns are printed with multiple sizes nested together. You can use this as a guide for pattern grading sewing.

Concept: Instead of just picking one size line, you draw a new line that smoothly connects the measurement points of different sizes.
When to use: This is good if your measurements fall between sizes, or if you are a different size on the top and bottom.

h5 Steps for Grading Between Sizes

Find your desired sizes: Based on your measurements, identify the size lines you need to use for different parts of the pattern piece. For example, maybe you need a size 14 at the bust, a size 16 at the waist, and a size 18 at the hip.
Trace the pattern piece: Trace the pattern piece, making sure to trace all the size lines that are relevant to you in the area you are working on (bust, waist, hip).
Draw a new line: Using your ruler and curved ruler, draw a smooth line that starts following the size 14 line at the bust, gradually curves out to follow the size 16 line at the waist, and then curves out further to follow the size 18 line at the hip.
Repeat for all pieces: Do this for all the pattern pieces that need this kind of adjustment (front bodice, back bodice, front skirt/pants, back skirt/pants).
Check everything: Make sure the new lines you drew connect smoothly. Check that side seams that will be sewn together are now the same length (measure them!).

This method is a form of scaling up sewing patterns by using the existing size information. It is easier than slash and spread if your measurements are close to the included sizes.

Applying Pattern Alteration Techniques

Beyond the main sizing up method, some general techniques help make your altered pattern work well. These help with fitting pattern to body accurately.

Using Extra Pattern Paper

As mentioned, tracing your original pattern is highly recommended. You can buy rolls of pattern tracing paper. Or use large sheets of tissue paper. Some people use newsprint (be careful of ink rubbing off). Adding extra paper when you slash and spread is a must. Tape it securely.

Blending Lines

After you spread a pattern piece and tape it down, the edges where you spread might be jagged or form steps. You need to draw smooth, flowing lines that connect the original lines and the new points. This is “truing” or “blending.”

Use a pencil so you can erase.
Use a curved ruler (like a French curve or a hip curve) to help draw smooth armholes, side seams, and hip curves.
Look at the original pattern lines. Try to keep a similar shape, just bigger.
Smooth lines help your fabric pieces sew together easily. Jagged lines will be hard to sew and will not look good.

Checking Grainlines

Every pattern piece has a grainline. This is a line with arrows on it. It shows how the pattern piece should be lined up with the fabric’s grain (the lengthwise threads).

When you alter a pattern, make sure the grainline stays straight. It should still be parallel to the selvage edge of your fabric.
Measure the distance from the grainline to the edge of your new, altered pattern piece at the top and bottom of the grainline. These distances should be the same.
If your alteration warped the grainline, redraw it correctly parallel to the original direction. The grainline is crucial for how the fabric hangs and behaves.

Adding to Specific Areas

Sometimes you do not need to spread the whole piece. You just need to add a bit of room in one spot.

For example, adding width to a waistband piece. If your waist measurement means you need 2 more inches around the waist, and the waistband is two pieces (front and back, or two sides), you add 1 inch to the length of each waistband pattern piece. You just add this to the short end that will be sewn to the center front or center back seam.
Adding length to a hem. Just draw a line parallel to the hem edge and add the desired length. Redraw the side seams to connect smoothly to the new hem edge. This is a simple resizing garment pattern task.

Walking the Seams

This is a pro tip for checking your alterations, especially with resizing garment pattern pieces that need to join. Before you cut fabric, “walk” the seams together on the paper pattern.

Line up the stitching lines (not the cut edges) of two pattern pieces that will be sewn together (like a side seam on a bodice and a skirt).
Pretend to sew them together by walking one piece along the other. Use a pin or your finger to follow the seam line.
Do they match up? Are they the same length? Do curves fit together smoothly (like the bodice side seam curve meeting the skirt side seam curve)?
If they do not match, you need to go back and adjust one or both pieces until they do. This saves a lot of headache when sewing!

Making a Muslin (Test Garment)

You have done all your pattern alteration techniques. You have resized garment pattern pieces. Now, before you cut into your nice, expensive fabric, make a test version. This test garment is called a “muslin.”

What to use: Use cheap fabric that is similar in weight and drape to your final fabric. Muslin fabric is cheap cotton and works well for many projects. Old sheets or scrap fabric work too.
How to make it: Sew the main seams of your altered pattern together. Use long stitches (basting stitches) so they are easy to take out. Do not worry about finishing edges, zippers, buttonholes, or hems. Just sew the basic structure (bodice front to back at sides/shoulders, attach sleeves, attach skirt/pants, sew waist seam).
Try it on: Put the muslin on. Pin it closed where zippers or buttons would go.
Check the fit: Look in a mirror. How does it feel? Is it too tight? Too loose? Does it pull anywhere? Are the seams in the right place (e.g., shoulder seam on top of your shoulder)?
Mark changes: Use pins or a pen to mark where you need more room or less room. Pin out excess fabric. Mark where it is too tight.
Take it off and adjust: Carefully take the muslin off. Lay it flat. Transfer the pin or pen marks onto the fabric. Open the basting stitches in the areas you need to change.
Transfer to pattern: Take your paper pattern pieces. Compare them to the changes you marked on the muslin. Lay the muslin flat on top of your paper pattern piece. Draw new lines on your paper pattern to match the changes you made on the muslin.
Refine the pattern: Re-tape and redraw your paper pattern based on the muslin fitting.

Making a muslin takes extra time and fabric. But it is the best way to ensure a good fit. It is part of the process of fitting pattern to body. It helps you catch mistakes before you cut your real fabric. For significant sizing up or complex patterns, a muslin is highly recommended. It really helps with scaling up sewing patterns and making sure the final result works.

Resizing Garment Pattern: A Summary

Let’s put the steps together simply. This is your guide to making a pattern larger for a better fit.

Measure Yourself: Get accurate body measurements for sewing. Write them down in your sewing pattern measurements guide (your notebook or table).
Compare to Pattern: Look at the pattern’s size chart. Compare your numbers. Figure out where you need to add size and how much. Remember ease.
Choose Your Method: Decide if you will use slash and spread for specific areas or grade between included sizes. Or a mix.
Trace the Pattern: Copy the original pattern pieces you need onto fresh paper. Mark important points like notches, dart lines, and grainlines.
Alter the Pattern: Use your chosen method (slash/spread, grading). Draw lines, cut, spread, tape onto new paper. Add the needed amount evenly across the piece.
Blend Lines: Draw smooth, new lines on your altered pattern pieces.
Check Grainlines: Make sure your grainlines are still straight.
Walk the Seams: Check that joining seams match up on paper.
Make a Muslin: (Highly Recommended!) Sew a test garment from cheap fabric.
Fit the Muslin: Try it on, check for fit, mark changes.
Refine Pattern: Transfer muslin changes back to your paper pattern.
Cut and Sew: Now you can cut your real fabric using your perfected pattern pieces!

This process is about making your sewing pattern measurements guide personal to you. It is a core part of pattern alteration techniques.

Common Mistakes When Sizing Up Patterns

Not measuring accurately: If your starting numbers are wrong, your pattern changes will be wrong too. Measure carefully.
Not accounting for ease: Adding your full measurement difference without considering the pattern’s built-in ease will make the garment too big. Look for finished garment measurements if possible.
Only altering one pattern piece: If you add width to the front bodice, you almost always need to add the same amount to the back bodice. If you change a side seam, the piece it attaches to (like a skirt or pants) needs a matching change.
Not blending lines smoothly: This leads to bumpy seams that are hard to sew and do not look good.
Not making a muslin: Skipping the test garment means you do not know if your alterations worked until you cut and sew your good fabric. This can be a costly mistake.
Adding size only at the side seams: While you can add a small amount this way, it distorts the shape of the pattern piece more than slashing and spreading. Spreading distributes the needed room more evenly.
Forgetting to adjust facings or linings: If you make a main pattern piece bigger, you need to make the matching facing, lining, or interlining piece bigger by the same amount in the same places.

FAQ: Questions About Sizing Up Sewing Patterns

h4 Is resizing a pattern the same as grading?
Not exactly. Pattern grading sewing is making a full range of sizes from a base size, following specific rules used in the clothing industry. As a home sewer, you often “grade between sizes” if the pattern includes them, which is a specific method of resizing garment pattern. “Sizing up” or “enlarging sewing patterns” is a broader term that includes methods like slash and spread or grading between sizes to make a pattern piece bigger for your needs.

h4 How much bigger can I make a pattern?
You can add a good amount of size using slash and spread, perhaps up to 2-4 inches total to an area like the bust or hip on a single pattern piece. However, making a pattern many sizes larger (say, jumping from a size 8 to a size 18) can change the overall proportions and shape of the pattern piece significantly. For major size increases, you might need more advanced pattern drafting knowledge or it might be easier to find a pattern closer to your size range if possible. Scaling up sewing patterns dramatically requires careful handling.

h4 Do I need to size up the facing pieces too?
Yes! If you make the main pattern piece bigger in an area where a facing or lining attaches, you must make the facing or lining piece bigger by the same amount in the same spot. Otherwise, they will not fit together.

h4 What if the pattern is too small in length, not width?
You can use slash and spread vertically to add length! Draw a horizontal line across the pattern piece where you need to add length (e.g., bodice above the waist, skirt below the hip). Slash the line and spread the piece downwards the amount of length you need to add. Fill the gap with paper. This is also part of pattern alteration techniques.

h4 My measurements are between sizes. Should I grade or pick the next size up?
If the pattern has nested sizes, grading between them is often the best way to get a smooth fit that matches your measurements exactly. If you just pick the next size up, it might be too big in some areas while still being too small in others. Interpreting pattern sizing means looking at all your measurements.

h4 How do I know where to draw the slash lines?
For adding overall width, vertical lines down the pattern piece are common. For specific changes like a Full Bust Adjustment (FBA), the lines are more complex, going from the armhole, through the bust point, and into a dart or the hem. Many sewing books and websites have diagrams for specific pattern adjustments for common fitting issues. Look for guides specific to the area you need to enlarge (bust, back, bicep, hip, etc.).

h4 What if I need to add size to knitted fabric patterns?
Patterns for knits have much less ease than patterns for woven fabrics because knits stretch. When sizing up a knit pattern, remember this. You might not need to add as much as you would for a woven pattern. Always check the finished garment measurements if available. The methods (slash/spread, grading) are similar, but the amount you add might be less.

Your Perfect Fit Awaits

Learning how to size up a sewing pattern is a skill that will greatly improve your sewing results. It takes a little extra time and patience, but the reward is clothing that truly fits you well. By taking body measurements for sewing, understanding pattern sizing, and using pattern alteration techniques like slash and spread or grading, you are taking control of your fit.

Do not be afraid to try it. Start with a simple pattern. Trace it carefully. Make small changes at first. And make a muslin! Each adjustment you make teaches you more about fitting pattern to body. Soon, resizing garment pattern pieces will feel natural. You will be able to make clothes that look like they were made just for you – because they were! Happy sewing and perfect fitting!