Unit Converter

One converter for the units people actually mix up

Travel, shopping, and health records still bounce between metric and imperial. A passport height in centimeters, a suitcase limit in pounds, and a weather app in Fahrenheit can appear in the same afternoon. This unit converter handles length, weight, and temperature with the exact factors used in science and trade, without sending your numbers anywhere.

Pick a category, pick the from and to units, and type a value. The result updates immediately. Switching category resets the unit pair to a sensible default so you do not accidentally convert “cm” as if it were a temperature.

The factors behind the results

Length conversions go through meters. An inch is exactly 0.0254 m, a foot is 0.3048 m, a yard is 0.9144 m, and a mile is 1,609.344 m. A kilometer is 1,000 m. That chain is why 180 cm is 1.8 m and 70.866 inches.

Mass conversions go through kilograms. A pound is exactly 0.45359237 kg. An ounce is 1/16 of a pound. A stone is 14 pounds. A metric ton is 1,000 kg. Temperature is not a factor conversion: it is an affine transform. Celsius to Fahrenheit multiplies by 9/5 and adds 32. Celsius to Kelvin adds 273.15. Mixing those formulas is the classic homework error; the tool applies the right one for the pair you selected.

How to use it

For height, convert cm to feet and inches by first converting cm to inches, then dividing by 12 for feet and reading the remainder. This page reports a single target unit, so “5 ft 10.9 in” is easier if you convert to inches (70.87) and split mentally, or convert to feet (5.91) and interpret the decimal.

For shipping, confirm whether the carrier means pounds or kilograms. A 23 kg bag limit is about 50.7 lb—not 23 lb. For weather, 0°C is freezing, 20°C is 68°F, and 30°C is 86°F. Negative Fahrenheit still exists; the formula does not care.

Examples

180 cm → 70.87 in. 5 miles → 8.047 km. 165 lb → 74.84 kg. 2.5 kg → 5.51 lb. 20°C → 68°F. 98.6°F → 37°C. 300 K → 26.85°C.

A 10 km race is 6.21 miles. A 26.2 mile marathon is 42.16 km. Those two numbers are why race shirts never agree across continents until someone converts them.

What we left out on purpose

Cooking cups, teaspoons, and “sticks of butter” change by country and by whether the cup is US legal, US customary, or metric. Including them without a locale switch creates bad cakes. Currency is not a unit conversion; it is a market price and would be stale if hardcoded.

If you need BMI after converting height and weight, use the BMI calculator next. It accepts both unit systems directly so you do not have to hop.

Typical examples

Frequently asked questions

How do you convert Celsius to Fahrenheit?

°F = °C × 9/5 + 32. The reverse is °C = (°F − 32) × 5/9. 20°C is 68°F; 32°F is 0°C; 100°C is 212°F.

How many centimeters are in an inch?

Exactly 2.54. That SI definition is what this converter uses, so 10 inches is 25.4 cm every time.

Is a pound the same as a kilogram?

No. One pound is 0.45359237 kilograms by definition. Kilograms measure mass; in everyday use people still say “weight” for both.

Do you convert volume or cooking units?

Not in this first version. Length, weight/mass, and temperature cover the highest-traffic everyday searches. Cooking cups vary by country, which is why they are easy to get wrong.

How precise are the results?

The math uses exact factors. Display rounding is to a readable number of decimals so a recipe or a height chart stays usable.