How this length converter works
Every unit you select is first converted to meters. Then meters are converted to your target unit. This makes conversions consistent and lets us support both metric and imperial plus special units like nautical miles.
Formulas
meters = value × factorToMeter[sourceUnit]
target value = meters ÷ factorToMeter[targetUnit]
Example: 5 miles to km:
5 × 1609.344 = 8046.72 m
8046.72 ÷ 1000 = 8.04672 km
Exact vs practical values
Some units are defined exactly (inch, foot, nautical mile); others you usually round for everyday use. This tool keeps the exact factors in the background but displays rounded results.
FAQ
1. Why is 1 in = 2.54 cm exactly?
Because the international yard and pound agreement fixed 1 inch = 2.54 centimeters exactly. So this is a defined conversion, not a measured one.
2. What is a nautical mile?
It’s used in navigation and aviation. 1 nmi = 1852 m exactly. It represents 1 minute of arc of latitude.
3. How accurate is this tool?
It uses standard exact definitions where available and enough decimal places for engineering and educational use.
Formula (LaTeX) + variables + units
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meters = value × factorToMeter[sourceUnit] target value = meters ÷ factorToMeter[targetUnit] Example: 5 miles to km: 5 × 1609.344 = 8046.72 m 8046.72 ÷ 1000 = 8.04672 km
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.