How to Sew a Muslin & Assess Fit!

Hey, you!

Writers write rough drafts. Professional chefs cook test recipes. And athletes practice to increase their skills and perfect their game.

And if this is your first time sewing any pattern, yes, you absolutely should sew a test garment, a muslin.

Muslins get a lot of hate, but…

I love sewing muslins!

Yes, you read right: I love sewing muslins!

And here’s the many reasons why…

NOTE: If you’re ready to begin this journey and would like to buy my recommended tools and supplies, please click HERE!

You Should Love Muslins Too!

  • You may find errors in the pattern. Yep, it happens. And I have.
  • You can make certain that the style will be flattering to you. This is how you “try on” a sewing pattern.
  • You can adjust the amount of ease to your liking.
  • You can determine your personalized fitting issues and refine the fit. This is of particular importance for fitted or semi-fitted silhouettes.
  • You can practice new or tricky techniques. For example, you don’t want to be installing an invisible zipper for the first time with your fashion fabric. Ask me how I know this?!
  • You can check pocket and button placement.
  • You can check neckline modesty level.

And what is really glorious about making a test garment…

  • You can save both money and time in the long run. Because once you find a pattern you love and you’ve fitted it to your liking, you now have a tried-and-true (TNT) pattern that you can play with and yield an infinite number of dresses simply by changing the fabric and style details!

Now, how awesome is that?!

Okay, I hope that I’ve convinced you of the beauty of sewing a muslin. Now, let’s learn how to do just that…

Two Key Tips to Sewing Muslins

i am muslin fabric

Before you learn how to sew a muslin, I need to share two things with you:

  • Your muslin can be the actual unbleached, cotton muslin fabric as pictured above. Yep, you sew a muslin with muslin fabric. Or, it can be an inexpensive fabric that has the same weight and drape as your fashion fabric.
  • Treat your muslin as if it is an exquisite length of the most luscious fabric that you’ve just shelled out $100/yard for.

Alright, it’s time to learn how to sew a muslin, step-by-step…

How to Prep Your Muslin

basic sewing pattern

Now, here’s the great thing…

A muslin is easy to sew. You only need to cut out the main pieces of the garment, such as the bodice front, bodice back and sleeves. No facings. No pockets. No hem.

And here’s how you do it…

First, gather your supplies: sewing pattern, removable Scotch tape, 2×18 ruler, seam gauge, marking tools, pins, shears, scissors, blue and red Sharpies, iron, and ironing board.

Then, do this…

  1. Set aside the main pattern pieces, such as the front and back of the garment and the sleeve.
  2. Press your pattern pieces with a dry, warm iron to remove all folds and creases.
  3. Trace a copy of your sewing pattern and extend the grain line along the entire length of the pattern piece. Remove the hem allowance from your traced pattern.
  4. Check the shoulder slope of your sewing pattern.
  5. Correct critical lengths: mid-shoulder to bust point; bust point to the waist; waist to hip; and back waist length.

lengthen/shorten adjustment lines on a tissue pattern

  1. Cut a length of muslin. (No, you don’t have to prewash.)
  2. Pin the selvages together.
  3. Straighten the grain if necessary.
  4. Place the front pattern piece on the muslin.
  5. With a seam gauge, add 3/8 inch to the 5/8 inch seam allowance to make 1″ SA at side and shoulder seams. This should give you plenty of room to add more width if you need to.
  6. Cut out the front pattern piece.
  7. Snip the center front at neckline and hem if it is not defined by a seam.
  8. Mark or snip dart legs, notches, and zipper stop.
  9. Pierce the dart point with a pin. Then, removed pins from shoulder and neckline. Fold the tissue pattern back and mark the dart point on both sides.
  10. Mark the wrong side of the muslin with an X.
  11. On the right side of the muslin, mark horizontal balance lines (HBLs) at the chest (notches), waist, and hip.
  12. Draw in the dart lines and seam lines.
  13. Repeat with back pattern piece and sleeves.

I’ve listed excellent resources, such as books and fitting patterns, in What You Need to Know to Fit a Sewing Pattern that can help you with this entire process.

Alright, remove the tissue pattern and you’re ready to put this baby together…

How to Sew Your Muslin

What you’ll need: conventional zipper and contrasting thread.

You’ll be machine basting your muslin pieces together.

  1. Staystitch the neckline and armholes, and then clip right up to the stitching line; press to WS.
  2. Sew all darts to the right side.
  3. Insert a zipper in the center back seam.
  4. Sew shoulder seams to the right side.
  5. With wrong sides together, try on the dress and pin fit the side seams to the contours of your body.

Pro tip: Always fit sleeves after you’ve adjusted the fit of the main garment.

That’s it!

You’re now ready to assess the fit…

How to Assess Fit

Now, that your muslin is basted together, you’re ready to assess the fit.

What you’ll need: a full-length mirror, a hand mirror, and a red Sharpie pen.

Try on your muslin with right side out. Because we wear our garments right side out, it is important that we assess it that way, especially if we have any asymmetries.

When assessing fit, you are looking for two things:

  • areas that look and/feel too big (gaping and sagging); or
  • areas that look and/feel too small (pulling, straining, pinching, and binding)

All you need to do as you make your assessments is to pin out excess fabric and use your red pen to mark the new stitching line along the line of pins.

Or, slash where it is too tight and measure how much it spreads.

In other words, use your muslin to pin fabric accurately to your curves and contours until you get the fit you want.

Order of Fit Assessment

You need to assess fit in this order:

Start at the back and at the top. In other words, check the fit at the upper back FIRST, and then the shoulder slope.

Because if you have a broad or rounded back or protruding shoulder blades, the front will NOT fit until you fit the back properly.

And since garments hang from our shoulders, the shoulder slope has to be right before you can accurately assess the rest.

To begin assessing…

FIRST, tie an elastic around your waist. And then, stand in front of a full-length mirror. Make sure you are looking straight ahead. Because turning distorts the fit of the garment!

SECOND, turn around so that your back is to the full-length mirror and hold up a hand mirror. And ask yourself the following:

  • How is the fit at the upper back?
  • Is the shoulder slope correct for your body? And are the shoulder seams smack dab in the middle of your shoulders and in line with your ears?
  • Check the lengths: Are the bustline, waistline, and hipline in the right places on your body?
  • Check the widths at the bust, waist, and hip: Is the garment comfortable to wear? Is the amount of ease to your liking?

The width of a garment consists of the body measurements for bust, waist, or hips plus ease.

  • Is there any straining or pulling around the zipper or buttons and buttonholes?
  • Do the darts point in the right direction and end at least ½ to 1 inch away from the curve they are shaping?
  • Do the neckline and armholes lie flat without gaping or binding?
  • Does the bodice fall smoothly across the upper back and chest to below the armholes?
  • Are all side seams perpendicular to the floor?
  • Is the hemline the same distance from the floor all the way around?
  • Finally, how does it feel to stroll around; bend over; sit down; cross your legs; reach forward; and reach way up?

illustration of good fit

Pro tip: Do NOT overfit! That means, do not remove minimum wearing ease –2 to 3 inches at the bust; 1 inch at the waist, and 2 to 4 inches at the hips– unless you enjoy walking like a mummy and being unable to sit or breathe.

The End

That’s it!

If you’ve taken accurate body measurements; chosen your starting pattern size; made basic pattern alterations; and sewed a muslin,  then…

You may very well be in possession of a tried-and-true (TNT) pattern that you can use over and over and over again to make an almost infinite amount of styles by just varying your fabric choice and playing with style lines.

And I have some really great news…

You are now ready to layout, cut, and mark your pattern on your fashion fabric!

I am so freaking ecstatic that we’ve gotten here!

And remember…

Life is the ultimate red carpet event. Dress for it!

RELATED: Click HERE to learn everything you need to know about sewing patterns so that you can flaunt the perfect fit!

RELATED: Click HERE to learn everything you need to know about fabric to sew insanely gorgeous dresses!

RELATED: Click HERE if you’re ready to begin this journey and would like to buy my recommended tools and supplies!

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