Unit Converter

Convert between metric and imperial units using exact international standard definitions.

Length

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Weight

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Temperature

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Sources

All length and weight conversions use the exact definitions from the 1959 International Yard and Pound Agreement (1 in = 2.54 cm exactly, 1 lb = 0.45359237 kg exactly) — no rounding shortcuts.

NIST Handbook 44, Appendix C — General Tables of Units of Measurement
NIST Special Publication 811 — Guide for the Use of the International System of Units (SI)