How to Use This Calculator
1. Set your units — choose Inches/Yards or cm/Metres with the toggle at the top. All inputs and results update together.
2. Enter finished length — how long you want the completed band to be, measured off the loom.
3. Adjust take-up, loom waste, fringe, and tying allowance — the defaults are good starting points for most backstrap or inkle-loom tablet weaving setups.
4. Choose holes per card — standard 4-hole cards are most common.
5. Add your colors — enter each color's name and how many cards use that color. The tool sums the cards and calculates per-color yardage.
6. Read results — see warp length per thread, total thread count, and exactly how many yards (or metres) of each color to wind.
Understanding the Formula
Warp length per thread = (Finished length ÷ (1 − shrinkage%)) × (1 + take-up%) + loom waste + (fringe × 2) + tying allowance
Threads per color = cards of that color × holes per card
Yardage per color = threads × warp length per thread (then add safety buffer %)
The 20% take-up is specific to tablet weaving: as the cards turn, the warp threads twist around each other, consuming more length than a regular shaft-loom project. Fringe is doubled because it appears at both ends of the band. The tying/knotting allowance (8–10 in / 20–25 cm) accounts for the length used when you tie the warp to your anchor point or wind off the tablets.
Frequently Asked Questions
For each card, you thread one warp thread through each hole — so a standard 4-hole card needs 4 threads per card. Multiply total cards by 4 to get total warp ends. Each thread must be long enough for your finished length × 1.2 (take-up) + loom waste (typically 20–30 in / 50–75 cm) + any fringe + 8–10 in for tying knots. Use this calculator to get the exact figure broken down by color.
Take-up is the length consumed as warp threads twist around each other and interlace with the weft. In tablet weaving the cards actively twist the warp, creating more interlacement than a shaft-loom plain weave. A 20% take-up factor (×1.2) is standard for most tablet-woven bands. If you're weaving a very densely turned pattern such as continuous warp-twining, add a few extra percent. If you're doing inkle (no card twist), 10% is more appropriate.
Warp length = (desired finished length × 1.2) + loom waste + fringe × 2 + tying allowance. For example: a 24-inch belt with 20 in loom waste, 3 in fringe each end, and 9 in tying allowance gives: 24 × 1.2 + 20 + 6 + 9 = 63.8 inches per thread. Always wind a little more than you think you need — unlike floor-loom weaving, it is very hard to splice extra warp onto a tablet-woven band mid-project.
Tablet weaving is warp-faced: the band width is determined by thread size and packing density. Wrap your thread around a ruler for 1 inch; count the wraps — that is your warp-per-inch density. Multiply by your desired band width (in inches) to get total warp threads, then divide by 4 (for 4-hole cards) to find the number of cards. This calculator works backward from the card count you've already planned.
Yes, with adjustments: inkle bands don't have card-twist take-up, so set take-up to 0% (or 5–10% if you're using a very thick, elastic yarn). Loom waste for inkle depends on your loom's peg path; measure the guide string for your chosen warp path and enter that value. Leave tying allowance at 0 for inkle — inkle warps are wound continuously, not tied off individually.
Loom waste is the warp length you cannot weave — the portion tied to your anchor point (doorknob, peg, or loom beam) and the section held within the tablet pack itself. For a typical backstrap or inkle loom setup, 20–24 inches (50–60 cm) is a common starting estimate. If you use a frame loom with tablets, measure from your back tie point to the tablet pack for a more accurate figure.
Most tablet-woven patterns specify which color goes in which hole (A, B, C, D) for each card. The color breakdown per card depends on your pattern draft. If a card has 2 threads of color A and 2 of color B, split that card's 4 threads accordingly in your calculations. This calculator lets you enter full cards per color — for mixed cards (e.g. half-and-half), enter 0.5 cards of each color, or split the thread counts manually using the per-thread yardage shown in the results.
Common choices include 10/2 mercerized cotton (approximately 4,200 yd/lb), 8/4 carpet warp cotton (unmercerized, very durable for beginners), wool worsted, and silk. Mercerized cotton produces a smoother, shinier band and is generally easier to work with than unmercerized. Wool adds elasticity and warmth but may shrink if wet-finished; use the shrinkage field in this calculator to account for that.