Estimate the starting chain for a pattern expressed as a multiple plus extra chains. This calculator selects the nearest whole repeat count, with at least one repeat, then adds the extras and turning chains. The result may be slightly narrower or wider than your target.
Use measured foundation-chain gauge, in chains per centimetre. The estimated width describes the relaxed starting chain excluding turning chains; it does not predict finished-fabric width.
Make a practice chain using your intended yarn, hook and tension. Lay it relaxed without stretching, count the chains spanning a measured section, and divide the count by that section’s length in centimetres. For example, 24 chains across 12 cm gives 2 chains/cm. Do not count the loop on the hook as a chain; see Basic Crochet Techniques.
Enter the number of foundation chains consumed by one pattern repeat. Enter width-bearing edge or balancing chains as extras, and enter additional turning chains separately. Count each chain only once. If a pattern’s “multiple plus” instruction already includes turning chains, split that allowance between the two inputs according to the pattern. Do not automatically add another turning chain allowance.
Use whole numbers for repeat, extra and turning-chain counts. Enter 1 as the multiple for a chain without repeat restrictions. These settings assume at least one complete repeat; patterns requiring several repeats or special edge arrangements need their own additional checks.
The formula is derived here from proportional measurement and the repeat constraint, rather than quoted as a published crochet formula. Width × chains per centimetre gives the unrounded width-bearing chain count. Subtract the extra width-bearing chains, divide by the repeat size, round the repeat count, then restore the extras and add turning chains. Thus (total chains − extras − turning chains) is always a multiple of the repeat size for valid integer inputs.
The one-repeat minimum is an explicit design choice. A very small target can therefore produce a much wider chain. Positive width difference means wider than requested; negative means narrower. This is nearest-fit rounding, not a guarantee to meet or exceed the target.
Foundation-chain gauge and finished-fabric gauge are different measurements. The Craft Yarn Council’s gauge chart describes gauges in worked stitches, including single crochet, rather than loose foundation chains. Do not substitute that chart or a yarn-label fabric gauge for your measured chain gauge. Work a pattern swatch to check finished width; stitch structure, tension and finishing can change the result.
The crochet sources explain foundation chains, turning chains and fabric gauge; they do not prescribe this calculator’s rounding policy. Invalid or unavailable results are not zero chains.
| Inputs | Repeat calculation | Starting chain | Estimated foundation width |
|---|---|---|---|
| 40 cm; 2 chains/cm; multiple 6; extras 2; turning 3 | (40 × 2 − 2) ÷ 6 = 13 repeats | 13 × 6 + 2 + 3 = 83 chains | 80 ÷ 2 = 40 cm; difference 0 cm |
| 41 cm; 2 chains/cm; multiple 6; extras 2; turning 3 | (41 × 2 − 2) ÷ 6 = 13.333… → 13 repeats | 13 × 6 + 2 + 3 = 83 chains | 80 ÷ 2 = 40 cm; difference −1 cm |
| 26 cm; 2 chains/cm; multiple 4; extras 2; turning 1 | (26 × 2 − 2) ÷ 4 = 12.5 → 13 repeats | 13 × 4 + 2 + 1 = 55 chains | 54 ÷ 2 = 27 cm; difference +1 cm |
| 1 cm; 2 chains/cm; multiple 6; extras 2; turning 3 | (1 × 2 − 2) ÷ 6 = 0 → minimum 1 repeat | 1 × 6 + 2 + 3 = 11 chains | 8 ÷ 2 = 4 cm; difference +3 cm |
Sources and method
- Crochet Guild of America — Basic Crochet Techniques: foundation-chain counting and turning-chain guidance.
- Craft Yarn Council — Standard Yarn Weight System: worked-fabric gauge context; not a source of foundation-chain gauge.
Draft production flag: no suitable registered thumbnail asset was supplied. Create and register a 400 × 400 pixel WebP thumbnail, then insert it as the first image block using its real asset ID. Inspect neighboring tool thumbnails before creation. Show the cheerful yellow five-point star mascot floating with hands, without separate legs or feet, beside a crochet hook, chain and measuring ruler on white, with playful navy, blue and teal educational graphics.