How do I know if shoulder width needs adjusting?

The shoulder seam should sit at the point of your shoulder (the bony bump). If the seam sits on your arm, the shoulders are too wide. If it digs into the top of your arm, they are too narrow.

How do I adjust shoulder slope?

Shoulder slope is adjusted at the armhole end of the shoulder seam. For sloping shoulders, lower the shoulder point. For square shoulders, raise it. This also affects the armhole and may need a corresponding sleeve adjustment.

Can I narrow broad shoulders on a finished garment?

Yes, by taking a deeper seam at the shoulder point and tapering to nothing at the neckline. This narrows the shoulder while maintaining the neckline position. You may need to adjust the sleeve head to match.

How does shoulder adjustment affect sleeves?

Changing the shoulder width or slope changes the armhole shape and size. The sleeve cap may need adjusting to fit the new armhole. Check the sleeve ease (usually 2-4cm) after adjusting the bodice shoulders.

SewCalcs

Shoulder Adjustment Calculator — Width & Slope

Calculate shoulder width and slope adjustments.

Current Shoulder Width

Across back, shoulder to shoulder

Desired Shoulder Width

Width measurement

Current Shoulder Slope

Drop from neck to shoulder point

Desired Shoulder Slope

Shoulder measurement

How We Calculate This

Shoulder adjustments are divided equally between both shoulders. Width changes are made at the armhole end; slope changes raise or lower the shoulder point.

The formula

Width adjustment = Desired - Current width

Per shoulder = Width adjustment ÷ 2

Slope adjustment = Desired slope - Current slope

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.