Convert units instantly with this free unit converter. Switch between centimetres and inches, millimetres and inches, kilograms and pounds, kilometres and miles, and Celsius and Fahrenheit. Exact formulas are shown below, along with quick reference values and FAQs. Ideal for homework, engineering, machining, DIY, fitness tracking and travel.
1 mile = 1.609344 kilometres
→ mi = km ÷ 1.609344, km = mi × 1.609344
Q: How do I convert centimetres to inches quickly?
Divide by 2.54. Example: 15 cm ÷ 2.54 ≈ 5.9055 in.
Q: What’s the difference between mm to inches and inches to mm?
They’re inverse operations: in = mm ÷ 25.4, mm = in × 25.4.
Q: Is kg to lbs exact?
Yes. Use lb = kg × 2.20462262185 (and kg = lb × 0.45359237).
Q: How many miles are in a kilometre?
1 km ≈ 0.62137 mi. The exact relation is 1 mi = 1.609344 km.
Q: How do I convert Celsius to Fahrenheit without a calculator?
Multiply by 9/5 and add 32. For a quick estimate, double °C and add 30.
Q: Can I change the number of decimal places?
Yes—use the Decimals control to increase or reduce precision.