Unit Converter
Metric meets imperial without the mental gymnastics: pick a category, choose your units, and get the exact conversion instantly.
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Last reviewed: July 20, 2026 · Formulas verified by automated tests before every release.
Common conversions worth memorizing
- 1 km ≈ 0.62 miles — or roughly: miles = km × 0.6
- 1 kg ≈ 2.2 pounds — a quick double-and-a-bit
- 1 inch = 2.54 cm exactly — the anchor of all length conversions
- °C to °F: double it and add 30 for a rough estimate (exact: ×9/5 + 32)
Why exact factors matter
Since 1959 the inch, foot, yard and pound have been defined exactly in metric terms by international agreement — so conversions aren't approximations, they're definitions. This converter uses those exact factors; only the displayed rounding is approximate.
Frequently asked questions
How do I convert kilometers to miles?
Multiply by 0.621371. So 10 km ≈ 6.21 miles. Going the other way, multiply miles by 1.60934.
How do I convert kilograms to pounds?
Multiply by 2.20462. So 70 kg ≈ 154.3 lb. One pound is exactly 0.45359237 kg.
What is the formula for Celsius to Fahrenheit?
°F = °C × 9/5 + 32. So 20°C = 68°F. For the reverse: °C = (°F − 32) × 5/9.
Are the conversion factors exact?
Length and weight factors are the internationally defined exact values (e.g., 1 inch = 25.4 mm exactly). Results are rounded to 6 decimal places for readability.