Conversion Calculator

One mile is defined as exactly 1.609344 kilometres by international agreement, so to convert kilometres to miles, divide by 1.609344 (or multiply by approximately 0.621371); to convert miles to kilometres, multiply by 1.609344.

For example, a 10 km race distance equals 10 ÷ 1.609344 ≈ 6.21 miles, and a marathon’s official 26.2-mile distance equals 26.2 × 1.609344 ≈ 42.16 km.

One kilogram equals exactly 2.20462 pounds (more precisely, 1 lb = 0.45359237 kg by international definition). To convert kilograms to pounds, multiply by 2.20462; to convert pounds to kilograms, multiply by 0.453592.

For example, 70 kg equals 70 × 2.20462 ≈ 154.3 pounds. Note that "weight" in everyday speech usually means mass in this context — technically, weight is a force that depends on gravity, while mass (measured in kilograms or pounds-mass) stays constant regardless of location. This calculator, like everyday usage, converts mass units.

Celsius to Fahrenheit: °F = °C × 9/5 + 32. Fahrenheit to Celsius: °C = (°F − 32) × 5/9. Celsius to Kelvin is simpler: K = °C + 273.15, since the Kelvin scale is offset from Celsius by a fixed amount rather than scaled differently.

For example, a comfortable room temperature of 22°C converts to 22 × 9/5 + 32 = 39.6 + 32 = 71.6°F. Useful anchor points: water freezes at 0°C / 32°F and boils at 100°C / 212°F at standard atmospheric pressure, and the two scales cross paths at exactly −40° (−40°C equals −40°F).

This calculator shows results to several decimal places so you can round appropriately for your context — a kitchen recipe rarely needs more than one decimal place in Celsius, while aviation, engineering, and scientific work may require additional significant figures.

• Do not confuse mass (kilograms, pounds) with weight as a force; everyday "weight" almost always means mass, which is what this tool converts.
• Airlines and carriers sometimes publish baggage limits in rounded, marketing-friendly numbers rather than exact conversions — always check the official limit enforced at check-in.
• Recipe conversions between metric and imperial volume (cups, millilitres) are separate from mass conversions and depend on ingredient density.

When converting oven temperatures for baking, round to the nearest 5°C or 10°F if your appliance dial lacks fine marks — a recipe calling for 180°C (356°F) usually works fine at 350°F in practice, though delicate pastry may need the closer value.

Runners training with a GPS watch set to kilometres but entering a US race advertised in miles can check pace targets by converting the race distance first — a 5 km park run is about 3.1 miles, not the "roughly 3" some mental math would suggest.

Online shopping from international sellers often lists product weight in pounds while local shipping labels expect kilograms. Converting 2.2 lb to exactly 1 kg (or 154 lb to about 70 kg for a baggage check) avoids surprise fees at the counter.

Medical and fitness contexts sometimes mix units on the same chart — body temperature in Fahrenheit on one app and Celsius on another, or medication doses in mg per kg. Temperature and mass conversions here cover the most common everyday switches; always follow clinician instructions for dose units rather than approximating.

After converting height and weight into matching units, the BMI Calculator and Ideal Weight Calculator can use those figures directly, and runners who just switched a race distance can continue into the Pace Calculator for split times.