Hem Calculator
Enter your desired finished length and hem type to get the exact cut length.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Hem Calculator
When cutting fabric for a garment, you need to add hem allowance to the finished length so the hem can be folded up and sewn. This calculator does that math instantly.
- Enter the desired finished length. This is how long the garment should be when worn — measured from the waist seam (or whatever seam is at the top of the piece) to the hemline.
- Enter the hem depth. This is how deep the hem fold will be. A standard skirt or pants hem is 1 to 2 inches. Curtains often use 3 to 4 inches. Shirt hems are typically 0.5 to 1 inch.
- Choose the hem type. Double fold hems are folded twice (the hem depth is used twice) for a cleaner finish. Single fold hems fold once. Blind hems use 1.5x the stated depth. Rolled hems use a smaller amount of fabric.
- Enter the top seam allowance. The default is 5/8" (0.625"). If the top of this piece will be sewn into a waistband or yoke, include the seam allowance here. Set to 0 if the top seam allowance is already accounted for elsewhere.
About the Hem Calculator
The cut length equals the desired finished length plus the hem allowance plus the top seam allowance. For a double fold hem, the fabric is folded to the hem depth and then folded again, so the total fabric consumed by the hem is twice the stated hem depth. For a single fold hem, only the depth is consumed. Blind hems are stitched at 1.5 times the stated depth to allow for the fold-back that makes the stitches invisible on the right side. Rolled hems use only half the stated depth since the raw edge is rolled and stitched.
Frequently Asked Questions
How much hem allowance should I add to a skirt?
For a typical skirt with a double fold hem, add 2 to 3 inches: 1 to 1.5 inches for the hem depth (folded twice). A 1" double fold hem uses 2" of fabric. A 1.5" double fold hem uses 3". For a lightweight fabric with a single fold and serged edge, 1 to 1.5" is sufficient. For formal skirts with a deep hem for weight and drape, you might use a 2" single fold hem (adding 2" to cut length).
What is the difference between a single and double fold hem?
A single fold hem folds the fabric once to the wrong side and stitches along the folded edge. The raw edge is either serged, pinking-sheared, or left as-is if it does not fray. A double fold hem folds the fabric twice — once to enclose the raw edge, then again for the finished hem. Double fold hems are cleaner, more durable, and more polished because no raw edge is exposed. They use twice the fabric of a single fold hem of the same depth.
How much hem do curtains need?
Curtains typically use a 3 to 4 inch double fold hem at the bottom (adding 6 to 8 inches to the cut length) to give the panels weight and a professional appearance. The top heading (rod pocket or pinch pleat area) adds another 4 to 8 inches depending on the style. The Curtain Size Calculator on this site handles all those calculations automatically if you prefer a complete curtain sizing solution.
Can I use this for pants hems?
Yes. For jeans and most pants, a 1" double fold hem (adding 2" to cut length) is standard. For dress pants with a more refined look, use a single fold blind hem of 1.5 to 2 inches. When altering store-bought pants, measure the inseam from the crotch seam down and add 1 to 2 inches for the hem, then cut. Try the pants on with shoes before marking the final hemline.