# Swatch-based yarn estimator

> Estimate yarn for a uniform flat piece from the area and weight of your own washed swatch.

- [Open tool](https://threadcabin.com/tools/swatch-yarn-estimator)
- The page shows its formula, example, assumptions, rounding, and limitations beside the calculator.

## Formula and assumptions

The target area is divided by the swatch area, then multiplied by swatch weight and allowance. Label length and weight convert that estimate to yarn length and whole balls. A visible ±15% planning band shows sensitivity, not a statistical guarantee. Use only for similarly constructed rectangular fabric with matching stitch pattern, gauge, and density.

## Worked example

Example: a 10 × 10 cm swatch weighing 5 g projects 165 g and 330 m for a 50 × 60 cm rectangle with 10% allowance, using 100 m per 50 g ball.

## Limits and rounding

Results are planning estimates from the values entered. Displayed decimals are rounded for craft use; whole materials and repeats round up where the method says so. Confirm gauge, material behavior, construction, and finished measurements before committing supplies.