KnitCalcs
Dart Calculator — Vertical & Horizontal Dart Placement
Calculate dart placement and shaping for fitted garments using vertical decreases or short rows.
How We Calculate This
This calculator converts dart dimensions to stitch and row counts and generates shaping instructions.
The formula
Vertical dart: Decrease interval = dart length in rows / number of decrease rows, where number of decrease rows = dart width in stitches / (2 x stitches decreased per side). Each shaping row removes one stitch on both sides of the dart marker, so the dart width is consumed in mirrored pairs.
Horizontal dart: Short rows = dart depth in rows (rounded to an even number, since short rows are worked in pairs). The dart width in stitches is then divided across the turns to give the stitches left unworked before each turn.
Frequently Asked Questions
Darts create shaping to accommodate body curves, most commonly for bust fitting. Vertical darts use paired decreases and increases. Horizontal darts use short rows. Both add extra fabric where needed for a closer fit.
Darts are most useful for fitted garments on bodies with a significant difference between bust and waist measurements. If the bust-to-waist difference is more than 8cm, darts improve fit. For looser styles, ease may be sufficient.
Vertical bust darts are placed at the side seam or about 4cm to each side of the centre front. The widest point should align with the bust point. Short-row darts are placed horizontally at bust point height.
Dart width depends on the difference between bust and waist measurements. A standard dart takes in 3-5cm at its widest point. Divide the total ease difference between front and back darts as needed.
Yes, some patterns use waist shaping (vertical darts at the sides) combined with bust darts (short rows at the front). This gives the best fit for bodies with both a defined waist and a full bust.
Related Calculators
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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.
Shoulder Shaping Calculator
Calculate short-row or bind-off shoulder shaping steps.
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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.