sewcalcs.uk
Length Adjustment Calculator — Lengthen or Shorten Patterns
Calculate how much to lengthen or shorten pattern pieces at the correct adjustment lines.
How We Calculate This
The adjustment is simply the difference between your desired length and the pattern length.
The formula
Adjustment = Desired length − Pattern length
Positive = lengthen (spread pattern). Negative = shorten (overlap pattern).
Frequently Asked Questions
Patterns have printed lengthen/shorten lines — horizontal double lines across the pattern piece. Cut along this line to spread (lengthen) or overlap (shorten). Never adjust at the hem line, as this changes the hem shape.
Draw your own adjustment line perpendicular to the grainline, midway between the waist and the hem (for skirts) or between the armhole and waist (for bodices). Keep it in a straight section, not across darts or shaping.
For bodice length, measure from the shoulder point (where shoulder meets neck) over the bust to the natural waist. For skirt length, measure from the waist to the desired hemline. Compare with the pattern measurement.
Related Calculators
Grading Calculator
Grade a pattern up or down between sizes with correct increments.
Sleeve Length Calculator
Calculate correct sleeve length from shoulder to wrist measurements.
Pattern Sizing Calculator
Find the right pattern size from your body measurements.
Pattern Scaling Calculator
Scale a pattern piece by percentage for enlarging or reducing.
Bust Adjustment Calculator
Calculate full bust or small bust adjustments for bodice patterns.
Was this calculator helpful?
Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.