How to Measure for Trousers: Inseam, Rise and Crotch Depth

Trousers are the garment most sewists find hardest to fit, and almost every problem traces back to a few measurements below the waist. Waist and hip get you started, but inseam, outseam and crotch depth decide whether a pant sits comfortably or pulls, sags and drags. This guide explains how to measure for trousers and pants step by step, including the measurements that a basic size chart often leaves out.

If you have not measured yourself before, our guide on how to take body measurements for sewing covers the basics of tape position and posture.

What you need and how to prepare

You only need a flexible tape measure, a length of narrow elastic or ribbon, a pencil and a notebook. A helper is very useful for the back measurements.

• Wear thin leggings or fitted underwear so the tape follows the real body line.
• Tie the elastic or ribbon around your natural waist and leave it there. It gives every vertical measurement a fixed starting point.
• Stand straight with feet about hip width apart and weight on both legs.
• Record body measurements only. The pattern adds the ease, so do not add extra room yourself.

Waist and hip: the two circumference measurements

1. Waist: measure at the elastic marker, around the narrowest part of the torso. For pull-on pants with an elastic or drawstring waist, this number tells you how long to cut the elastic, but the waist of the garment itself must still pass over your hips.
2. Hip: measure around the fullest part of the seat, keeping the tape level from the side. Look in a mirror to check that the tape has not dropped at the back.

For pull-on styles, the hip is usually the controlling measurement, because the finished waist must stretch over it.

That is why pull-on designs such as the Metro Pant and the Breeze Pant are generous through the waist before the elastic or drawstring gathers it in.

Crotch depth (also called rise)

Crotch depth is the distance from the waist down to the base of the body between the legs. It is the single most important measurement for comfortable trousers. Too short and the pant cuts in; too long and the seat sags.

The seated method

1. Sit upright on a firm, flat chair, thighs parallel to the floor.
2. Measure at the side of the body from the waist marker straight down to the chair seat.
3. Keep the tape vertical, following the hip curve rather than pulling it tight.

This number is your crotch depth. Write it next to your waist and hip.

Crotch length (total rise)

For a more detailed check, measure from the centre front waist, down between the legs, and up to the centre back waist. Ask a helper to read the number at the back. It shows how the rise is shared between front and back, which helps if you later adjust a pattern.

Inseam and outseam: getting the leg length right

• Inseam: measure from the crotch down the inside of the leg to where you want the hem to finish. The easiest way is to measure a pair of well-fitting trousers along the inside leg seam.
• Outseam: measure along the side of the leg from the waist marker down to the desired hem point.

The two numbers should roughly add up: outseam minus crotch depth gives an approximate inseam. If they disagree by a lot, measure again.

Decide the finished length wearing the shoes you plan to wear. Wide legs usually look best a little longer, while narrow legs often finish at the ankle.

Thigh, knee and ankle

These are optional but helpful, especially for narrower styles:

• Thigh: around the fullest part of one thigh, just below the crotch.
• Knee: around the knee with the leg straight.
• Ankle or hem opening: decide how wide you want the hem, then check it passes comfortably over your foot.

A roomy shalwar-style pant hardly needs these, but for a narrow-leg trouser they help prevent tightness when you sit or climb stairs.

Shalwar versus tailored trousers

Different trouser styles use your measurements in different ways:

• A shalwar-style pant such as the Breeze Pant is cut very roomy, with one piece per leg and a gathered drawstring or elastic waist. Hip and length matter most; small differences elsewhere are absorbed by the fullness.
• A tailored pull-on pant such as the Metro Pant has separate front and back pieces and narrow, straight or wide legs. Crotch depth, hip and inseam matter much more here.

Both are listed as beginner-level designs in the Digital Creation collection, which makes them a good first project for practising trouser fit.

Frequently asked questions

Is crotch depth the same as rise?

Yes, the terms are often used for the same measurement: the vertical distance from waist to seat when sitting.

Can I take my inseam from existing trousers?

Yes. Lay a well-fitting pair flat and measure along the inside leg seam from the crotch point to the hem. It is often more accurate than measuring yourself.

Once your numbers are written down, open the pattern builder, choose a pant style and enter your own measurements or a standard size. You can preview every design for free and check the Pricing page when you are ready to download.