KnitCalcs
Armhole Calculator — Depth & Bind-Off Shaping
Calculate armhole depth, initial bind-off, and shaping decreases for fitted garments.
How We Calculate This
This calculator estimates set-in armhole shaping from your chest circumference, desired depth and gauge. The per-side reduction is the difference between the body width and the cross-back (shoulder) width, halved.
The formula
Per-side reduction ≈ 4–5% of chest circumference (the body-to-cross-back difference, divided by two)
Initial underarm bind-off ≈ 30–40% of that reduction
Remaining stitches worked as gradual decreases every RS row
Frequently Asked Questions
Standard armhole depth is 18-25cm for adults, depending on garment size and style. Measure from the underarm to the top of the shoulder. Closer-fitting garments have shallower armholes; drop-shoulder styles have deeper ones.
The initial underarm bind-off is small — about 1.5-3.5cm of stitches (often only 4-8 sts), cast off across the first one or two rows. This is far less than the total armhole reduction. The remaining shaping is worked as gradual single-stitch decreases on right-side rows, not bound off, which gives a smooth curved armscye.
Shaped armholes curve inward with bind-offs and decreases, giving a fitted look. Drop-shoulder armholes are straight with no shaping - the sleeve hangs below the actual shoulder. Modified drop shoulders have minimal shaping.
Work the same bind-off and decrease sequence on both front and back pieces. Mark the beginning of armhole shaping with stitch markers and count rows carefully. For knitting in the round, place markers at both underarm points.
Yes. Set-in sleeves need a standard-depth armhole. Cap sleeves need a shallower armhole. Dolman or batwing sleeves need a very deep armhole extending nearly to the waist.
Related Calculators
Shoulder Shaping Calculator
Calculate short-row or bind-off shoulder shaping steps.
Dart Calculator
Calculate vertical or horizontal dart placement for fitted garments.
Raglan Calculator
Calculate raglan decrease rates and yoke depth for top-down or bottom-up construction.
Set-In Sleeve Calculator
Calculate sleeve cap shaping for set-in sleeve construction.
Neckline Calculator
Calculate neckline shaping for round, V-neck, and boat neck styles.
Was this calculator helpful?
Last updated: February 2026
All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.