Crotch Depth / Rise Calculator
Take one sitting measurement and get exact front and back rise adjustments — accounting for belly prominence and seat shape.
Enter your measurements
Take your sitting measurement first, then measure the rise on your pattern pieces.
Waist to chair seat, seated upright
Waist seamline to crotch point (front)
Waist seamline to crotch point (back)
Your body shape
How to take your sitting measurement
Sit upright on a hard, flat chair — a dining chair is ideal. Wearing what you normally wear (no thick padding). Sit so your thighs are parallel to the floor and your back is straight.
Place the tape measure at your natural waist (the narrowest point, usually about 1" above your navel). Run the tape straight down the side of your hip to the seat of the chair. That measurement is your crotch depth.
Most sewers find their sitting measurement is about 1–2" less than their pattern's front rise — the difference is ease. If your sitting measurement is very close to or longer than the front rise on the pattern, you almost certainly need to lengthen.
How to measure the pattern rise
Lay the front pattern piece flat. The front rise is measured from the waist seamline (not the cut edge) straight down to the crotch point — the corner where the inseam and crotch seam meet.
For the back rise, do the same on the back pattern piece. The back rise is always longer than the front rise on a well-fitting pattern — typically 2–4" longer.
Do not include seam allowances in your measurements. If the crotch curve is complex, measure along the seamline using a flexible tape or a piece of string.