Step by step

The test garment: sew, try on, adjust

A test garment shows you whether the pattern fits before you cut into your good fabric. How to choose the fabric, sew it quickly, read the wrinkles and transfer changes to the pattern.

On the left a top from the front with diagonal drag lines from the bust point to the side (too tight). On the right a top from the back with loose, wavy folds in the lower back (too much fabric)

With every made-to-measure pattern and every new pattern we say: sew a test garment first. It sounds like a detour, but it saves fabric, time and frustration. In the end a pattern is a calculation, and your body and your fabric don't always follow calculations.

A test garment doesn't have to be pretty. It just has to be honest: made from a fabric that behaves similarly, sewn quickly and tried on thoroughly. Here's how, and how to turn what you see into a change.

What you need

Inexpensive fabric with similar stretch to your final fabric (scraps, old T-shirts, bedding)
Ruler or tape measure
Chalk or a fabric marker
Pins
Basting thread or thread in a contrasting colour
Mirror and phone for photos

Step 1

Choosing the right test fabric

On the left a fabric strip on a ruler and below it the same strip stretched and longer. On the right two different fabric strips that stretch the same distance (right)

A test garment only tells you about the fit if its fabric behaves like the final one. For jersey and knits, stretch matters most.

Here's the stretch test: mark 10 cm across the grain, gently stretch the fabric along a ruler until you feel resistance, and read the length. 13.5 cm means 35 % stretch. Test both fabrics; they should be within a few percent of each other.

For jersey patterns (Merl, Han, Pulo, Wleg): inexpensive jersey, old T-shirts or jersey bedding with similar stretch and similar thickness.
For wovens: an old bed sheet or calico.

Step 2

Sewing it quickly and simply

On the left a front piece with the centre line, waist and hip lines drawn on and a cross at the bust point. On the right front and back pieces on top of each other, with pins and long basting stitches along the side seam

Only what you need to check: the main pieces and one sleeve. Leave out neckband, lace, pockets and hems; just press the hems under.
Transfer the lines: waist, hip, centre front and back and the bust point, with chalk or a fabric marker on the right side. These lines later show you whether something sits crooked.
Long stitches: stitch length 4 to 5 mm or basting, so you can unpick easily. For jersey use a long, narrow zigzag so the seam doesn't snap when you put it on.
Don't trim or finish the seam allowances. If you need extra width somewhere, you can let it out there.

Step 3

Trying it on properly

On the left a figure in the test garment lifting its arms. On the right a phone with three photos of the same figure: front, side and back

Wear what you'll wear underneath: the same underwear, the same bra. For trousers and dresses, the shoes you'll wear with them.
Move: lift your arms, sit down, bend over, walk a few steps. A test garment that only fits while standing still doesn't fit.
Take photos: from the front, side and back, from about two metres away, camera at waist height. Photos show things you don't notice in the mirror.
Look at the lines: do waist and hip run level? Do the side seams hang straight down? Does the shoulder seam sit on top of your shoulder?

Step 4

Reading the wrinkles

Wrinkles tell you what the pattern needs. There are two kinds:

Drag lines are taut and run diagonally. They point to where width or length is missing. Drag lines from the bust to the armpit, for example, mean there's too little width at the bust.
Loose horizontal folds lie slack and wavy. There's too much fabric there, usually too much length. Ripples in the lower back above the seat often mean the back can be shorter there.

Lines help too: if the hem rises at the front, length is missing at the front. If trousers pull in the crotch, the crotch length is too short.

Step 5

Pinning and measuring

On the left a pinned fold in the fabric with three pins and a measuring arrow across the fold. On the right an unpicked seam with a gap and a measuring arrow across it

Too much fabric: pin the excess out as a fold until it lies smooth, the same on both sides. Measure the fold from the pin line to the fold edge and double it: that's how much is too much.
Too little fabric: unpick the seam there until the fabric lies smooth. Measure the gap between the edges: that's how much is missing.
Write it down: where (e.g. side seam at waist level), how much, and whether more or less. Take a photo with the pins in.

Change only one thing at a time, then try it on again. Sometimes one change solves two problems at once.

Step 6

Transferring changes to the pattern

On the left a paper pattern with a newly drawn dashed side seam that moves slightly inward at the waist, and a magnifier on the change. On the right a notepad with ticked lines and a pencil

Redraw the line: mark the change at the measured spot and blend it smoothly to the next corner or notch, with no kink.
Change the matching piece too: if a side seam gets shorter at the front, the back has to stay the same length. Move notches if a length changes.
For made-to-measure, check your measurements first: a big difference often means a measurement was taken differently, for example the hip too high. Read Taking your measurements again.
When pattern testing: send your notes and photos via your feedback page. That's exactly what helps us make the pattern better for everyone.

A second test garment is only worth it for big changes. You can sew small corrections straight into the real fabric.