Unit Converter

All factors are exact international definitions rather than rounded approximations, so results stay accurate at any scale.

How to use the unit converter

Choose a category such as Length or Weight.

Enter your value and pick the unit it is in.

Choose the unit to convert to – the result appears instantly.

Why use the Convert Now unit converter

Eight categories

Length, weight, volume, area, speed, time, temperature and data.

Exact factors

International definitions, not rounded approximations.

Shows the factor

See the conversion rate as well as the answer.

Instant

Results update as you type.

Exact factors, not approximations

Many converters round their factors, which introduces error that grows with the size of the number. We use the internationally defined values: an inch is exactly 25.4 millimetres, a pound is exactly 0.45359237 kilograms, a mile is exactly 1609.344 metres. These are definitions rather than measurements, so conversions are exact and remain accurate whether you are converting a millimetre or a marathon.

Temperature is different

Length and weight conversions are simple multiplications, because zero means the same thing in both units. Temperature scales have different zero points, so converting requires an offset as well as a scale: Celsius to Fahrenheit multiplies by 9/5 and then adds 32. That is why you cannot convert a temperature difference the same way you convert a temperature, and why the calculator handles this category separately.

Decimal versus binary storage units

A kilobyte can mean 1,000 bytes or 1,024 bytes depending on who is counting. Storage manufacturers use the decimal definition; operating systems have traditionally used the binary one, which is why a 1 TB drive shows up as roughly 931 GB in Windows. Both are offered here – KB, MB, GB and TB are decimal, while MiB and GiB are the unambiguous binary units.

Read the guide: What Is a Good BMI? Healthy Ranges Explained

Frequently asked questions

How do I convert cm to inches?

Choose Length, enter your value in centimetres and select inches as the target. One inch is exactly 2.54 cm.

How do I convert kg to pounds?

Choose Weight and select kg and lb. One kilogram is about 2.20462 pounds.

How do I convert Celsius to Fahrenheit?

Choose Temperature. The formula is (°C × 9/5) + 32, which the converter applies automatically.

Why does my 1 TB drive show as 931 GB?

Manufacturers count 1 TB as 1,000,000,000,000 bytes while operating systems often use binary units. Convert TB to GiB in the storage category to see the same number your computer reports.

Are the conversion factors exact?

Yes. We use internationally defined values, so results are accurate at any magnitude.

How many units are supported?

Over 50 units across eight categories, including nautical miles, hectares, knots, stones and binary storage units.