Length Converter

How to use the Length Converter

Convert between common metric and imperial distance units using standard exact or defined conversion factors.

Convert common metric, imperial, and US customary length units while keeping the selected input as the source of truth. Swap source and destination units in one action and choose 0–10 displayed decimal places.

The conversion runs locally using the stated factors or formulas. Keep enough precision for the task and verify regulated or engineering work against its controlling standard.

1. Enter a numeric value.
2. Choose the source unit and destination unit.
3. Fieldlet converts the source value through meters and displays the equivalent destination value.

Last reviewed for accuracy: 2026-08-31

Worked examples

How the result is produced

Fieldlet converts the input to a common meter base using defined factors, then converts from meters to the requested output. This avoids chaining several rounded intermediate conversions.

• 1 inch = exactly 2.54 centimeters
• 1 international foot = exactly 0.3048 meters
• 1 international mile = exactly 1,609.344 meters

Exact factors and displayed precision

Several relationships, including inch-to-centimeter, are defined exactly. A decimal display can still be rounded because the converted number may not terminate in the chosen unit.

• Keep extra digits during intermediate work.
• Round once at the end to the precision the task supports.
• Do not imply more measurement accuracy than the original value contains.

References

These primary references document standards or definitions used in the explanation above.

• NIST SI unit information

Limitations and common mistakes

• Survey feet and historical local units can differ from the international definitions used here.
• Construction and engineering tolerances may require specified rounding, significant figures, or calibrated measurements.

Common questions