About
Built for speed and accuracy.
Free Length Converter is a free online tool that converts between length units instantly. Whether you need to convert inches to centimeters for a design project, miles to kilometers for a road trip, or angstroms to nanometers for research — we've got you covered.
Every conversion runs entirely in your browser. There is no backend and no account required. Your conversion inputs stay on your device; we use Google Analytics only for aggregated page-view statistics.
Three conversion methods.
- Standard units — everyday metric and imperial (mm, cm, m, km, in, ft, yd, mi).
- Metric & Imperial — full SI ladder, survey units, feet+inches input, fraction output.
- Scientific units — angstroms, light-years, parsecs, Planck length, and more.
Why we built this.
Most length converters online are cluttered with ads, slow to load, and stuck in outdated designs. We wanted something better: a clean, modern interface that loads fast, works on any device, supports dark mode, and uses exact conversion factors.
Accuracy.
All conversions use internationally defined exact factors. For example, 1 inch = 25.4 mm, 1 foot = 0.3048 m, and 1 mile = 1,609.344 m. We compute with double-precision floating point and format results for readability without sacrificing accuracy.
Supported units.
51 length units across standard, metric/imperial, and scientific categories.
Contact.
Free Length Converter is maintained as an open utility at freelengthconverter.com.