Convert between common metric length or mass units and see the multiplying factor. This free tool is useful for checking school-distance, ruler and weighing questions during maths practice in Kenya.
Choose units of the same kind
For length, choose mm, cm, m or km. For mass, choose mg, g or kg. The tool rejects a conversion from length to mass because those measure different quantities. It does not convert litres, area, volume, temperature or imperial units.
How metric conversion works
The prefixes describe powers of ten. Kilo means 1,000 times a unit, centi means one hundredth, and milli means one thousandth. To convert, write the measurement in a common base unit, then divide by the size of the unit you want. The result shows the single multiplication factor for that pair.
Worked examples for school practice
A journey to school is 2.5 km. Since each kilometre is 1,000 metres, 2.5 × 1,000 = 2,500 m. A pencil is 18 cm long: 18 × 10 = 180 mm. In the other direction, 180 mm ÷ 10 = 18 cm.
A bag of beans has a mass of 2,500 g. Divide by 1,000 to express it in kilograms: 2,500 ÷ 1,000 = 2.5 kg. Keep the unit alongside every answer; the number alone does not say what you measured.
Check your answer
Converting to a smaller unit should give a larger numerical value. For example, a metre contains many millimetres. Converting to a larger unit should give a smaller numerical value. Use that quick sense check before you trust a calculator answer.
Enter non-negative finite values up to 1 trillion. Answers are displayed to at most 12 significant digits. Zero is accepted, and converting a unit to itself leaves the number unchanged.
This is a free, independent learning aid for Kenyan families and teachers. It does not produce an examination grade or placement prediction. The calculator works on this device: it does not send or save the values you type.
More maths practice
Try the Grade 5 Mathematics papers or Grade 6 Mathematics papers. Our decimals revision guide helps with powers of ten. See all free tools.
Official measurement source
Prefix factors follow the International Bureau of Weights and Measures (BIPM) SI prefixes table. Kilo is 10 to the power 3, centi is 10 to the power -2 and milli is 10 to the power -3. Examples and tool implementation are our own. Source checked 7 November 2026.
Frequently Asked Questions
How many metres are in 2.5 kilometres?
There are 2,500 metres. Multiply kilometres by 1,000 to convert to metres.
How do I change grams to kilograms?
Divide the number of grams by 1,000. For example, 2,500 grams equals 2.5 kilograms.
Why can I not convert metres to kilograms?
Metres measure length and kilograms measure mass. There is no general conversion between these different quantities.
Are my measurements stored?
No. The conversion runs in your browser and does not send or store the values you enter.