Sewing calculator
Seam Allowance Calculator: Finished Size to Cut Size
Add independent seam and hem allowances to a finished width and height to get the cut size before you mark fabric.
Your measurements
Seam and hem result
- Cut width
- 43.00 in
- Cut height
- 43.00 in
Formula
Cut width equals finished width plus left and right allowances; cut height adds top and bottom allowances.
Assumptions
- Allowances are measured perpendicular to each edge.
- Each edge entry represents the complete allowance required by that edge treatment.
When a tested commercial pattern gives different cutting dimensions or layout instructions, follow that pattern.
Worked example
- 40 × 38 in finished rectangle
- 1.5 in left and right · 1 in top · 4 in bottom
The independent edge allowances produce a 43 × 43 inch cut rectangle.
Verification note
Confirm whether the source measurement is a finished line or an existing cut line before adding anything.
Learn and verify
Questions from search
How do I turn a finished size into a cut size?
Add the left and right allowances to the finished width, and the top and bottom allowances to the finished height. Each edge can use a different amount.
Is seam allowance the same as a hem?
No. A seam allowance is the fabric inside a join. A hem allowance is the fabric folded at a finished edge. Enter them on the edges where each one applies.