Measure twice, make once
Measurement converter
Convert craft lengths and masses between metric and imperial units.
Start with the calculator. Formula, assumptions, and limits are available when you need them.
Before you use this tool
Select the unit printed beside the original number, then the desired output unit. Convert length to length or mass to mass.
For yarn, grams cannot become metres without that yarn’s label ratio. More precision changes the displayed digits; it does not make the measured input more accurate.
Method and limits
Formula and assumptions
Length and mass conversions use exact standard factors before the displayed value is rounded. Length cannot be converted directly to mass.
Worked example
Example: 100 centimetres displays as about 39.4 inches at practical precision; the optional detail control shows 39.3701.
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.