Sleeve Ease Calculator

Sleeve Cap Height affects how tall and rounded a sleeve cap curve is on the pattern piece itself, but the amount of cap ease this calculator recommends is set purely by Sleeve Type and scaled from Armhole Circumference. The two measurements answer different questions -- cap height is about the shape of the curve, cap ease is about how much fabric that curve holds beyond the armhole -- so entering a different cap height has no effect on any output here.

Sleeve Cap Circumference is simply Armhole Circumference plus the fixed Cap Ease Amount for the sleeve type you picked. Because that ease amount doesn't change with armhole size, every additional inch of armhole circumference adds exactly one inch to the target sleeve cap circumference.

Of the four types this calculator supports, Set-in Sleeve carries the most cap ease at 1.5 in -- its tall, rounded cap has to be eased over the shoulder curve. Shirt Sleeve carries only 0.75 in (a shallow cap, set in flat, in a crisp fabric that puckers easily) and Raglan Sleeve 0.5 in. Drop Shoulder carries none (0 in) because its seam sits away from the shoulder point entirely, so there is no rounded cap curve that needs easing into the armhole.

The calculator distributes the total Cap Ease Amount roughly 60% to the top of the cap (Top Cap Ease) and 40% to the underarm area (Under-arm Ease), reflecting that most sleeve caps need more easing fullness over the shoulder curve than along the straighter underarm seam. Both figures are simple fixed fractions of the same Cap Ease Amount, so they scale together with sleeve type, not with armhole circumference.