How to Use Length Converter
The Length Converter updates all nine unit fields instantly from a single entry.
- Type a Value in Any Field — Enter a number in mm, cm, m, km, inches, feet, yards, miles, or nautical miles. The Length Converter populates all other fields the moment you type.
- Choose Display Precision — Use the precision selector to show 2, 4, or 8 significant figures depending on how much detail you need.
- Copy Any Result — Click the copy icon next to any field to copy that value to your clipboard for use in documents, spreadsheets, or forms.
- Use the Swap Button — Click Swap to exchange the source and target fields, making common round-trip conversions (km ↔ miles, cm ↔ inches) a single click.
Formula & Theory — Length Converter
The Length Converter converts through metres as the internal base unit:
metres = input × factor_to_metres
output = metres / factor_to_metres| Unit | Metres (exact or NIST-defined) |
|---|---|
| 1 mm | 0.001 m |
| 1 cm | 0.01 m |
| 1 inch | 0.0254 m (exact) |
| 1 foot | 0.3048 m (exact) |
| 1 yard | 0.9144 m (exact) |
| 1 mile | 1,609.344 m (exact) |
| 1 nautical mi | 1,852 m (exact, IMO definition) |
| 1 km | 1,000 m |
Quick Reference: Common Conversions
| From | To | Factor |
|---|---|---|
| 1 foot | cm | 30.48 |
| 1 inch | cm | 2.54 |
| 1 mile | km | 1.60934 |
| 1 km | miles | 0.62137 |
| 1 nautical mi | km | 1.852 |
Use Cases for Length Converter
The Length Converter is one of the most universally needed calculation tools:
- Construction and architecture — Switch seamlessly between metric blueprints from European suppliers and imperial measurements used on North American job sites.
- International e-commerce — Convert product dimensions between inches and centimetres to verify fit before purchase or to complete customs declaration forms.
- Fitness and running — Convert race distances between kilometres and miles (5K, 10K, marathon) or calculate training pace in both unit systems.
- Science and engineering education — Unit conversion homework and dimensional analysis exercises are verified instantly with the Length Converter.
- Travel and navigation — Convert road distances from miles to kilometres for European travel, or nautical miles to kilometres for sailing route planning.
- Woodworking and DIY projects — Convert between inches and millimetres when working from plans with mixed units, or when ordering materials from international suppliers.