sewcalcs.uk
Hook and Eye Calculator — Spacing & Quantity
Calculate hook and eye spacing and quantities for closures.
How We Calculate This
Hooks and eyes are stepped along the closure at the fixed spacing, starting at the top offset. The bottom offset sets the minimum clear gap left below the last hook, so it reduces the quantity that fits but does not change the spacing. The quantity is determined by the closure length, both offsets and the desired spacing.
The formula
Usable length = Closure length − Top offset − Bottom offset
Quantity = floor(Usable length ÷ Spacing) + 1
Positions are stepped from the top edge at the fixed spacing (Top offset, then +Spacing each set). Because hooks step from the top, the actual gap below the last hook may be larger than the bottom offset — that figure only sets the minimum clearance. Thread estimate ≈ Quantity × Stitches per hook × Thread per stitch × 2 (hook + eye), assuming ~2 cm per hand stitch over 4–6 stitches per hole (TREASURIE / MadamSew).
Frequently Asked Questions
For waistbands, one hook and eye is often sufficient. For back bodice closures, space them 2-3cm apart. Corset-style closures need 1.5-2cm spacing. Closer spacing gives a more secure closure.
Size 0-1 for lightweight fabrics and delicate closures. Size 2-3 for medium weight. Size 4+ for heavy fabrics and areas of strain. Use flat (trouser) hooks for waistbands and round hooks for bodice closures.
Use matching thread and a small hand needle. Sew through each hole or loop with 4-5 stitches. Place the hook on the overlap side, slightly back from the edge. Place the eye on the underlap, extending slightly beyond the edge.
Hooks and eyes work best on stable, non-stretch fabric. On stretchy fabric, they can pop open. For stretch closures, use snaps or hook-and-loop tape instead. Interface the closure area for added stability.
Related Calculators
Snap Spacing Calculator
Calculate even snap placement and quantities.
Velcro Calculator
Calculate hook-and-loop tape length for closures and fastenings.
Button Spacing Calculator
Calculate even button spacing and placement for garments.
Boning Calculator
Calculate boning lengths and quantities for corsets and bodices.
Elastic Calculator
Calculate elastic length for waistbands, cuffs and casings.
Was this calculator helpful?
Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.