Crochet Calculator
Calculate crochet gauge, foundation chains, rows and approximate stitch count from a swatch and project size.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Every crochet pattern starts from a gauge swatch, because the same yarn and hook produce different fabric in different hands. Once you know how many stitches you personally get per four inches, converting any finished size into a stitch count is simple arithmetic.
Worked example
calculated with the default values below
Stitches in your swatch 16 · Rows in your swatch 18 · Swatch size 4 in · Desired project width 40 in · Desired project height 30 in · Extra foundation chains 2 Your stitches per inch 4.00 · Your rows per inch 4.50 · Foundation chains 162 · Rows needed 135 · Total stitches crocheted 21,870
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
N = (round(W × s ÷ w) + e) × round(H × r ÷ w)
- s
- Swatch stitches
- r
- Swatch rows
- w
- Swatch size (in)
- W
- Project width (in)
- H
- Project height (in)
- e
- Extra foundation chains
Stitches per inch = s ÷ w; rows per inch = r ÷ w. Total stitches are an approximate chains × rows count; yarn quantity is not estimated.
Frequently asked questions
How do I calculate foundation chains and rows?
The calculator derives stitch and row gauge from your swatch, then multiplies by the desired project dimensions and rounds to whole counts. Foundation chains include the extra chains you enter. Total stitches are an approximate chains-times-rows count; shaping and stitch patterns can change it. Yarn quantity is not estimated because it also depends on yarn, hook, stitch pattern and tension.