20 km to mm — 20 kilometres in millimetres
Exact 20 × 1,000,000 = 20,000,000
20 kilometres in other units
| Nanometres | 20,000,000,000,000 | nm |
|---|---|---|
| Micrometres | 20,000,000,000 | µm |
| Millimetres | 20,000,000 | mm |
| Centimetres | 2,000,000 | cm |
| Metres | 20,000 | m |
| Inches | 787,401.57 | in |
| Feet | 65,616.8 | ft |
| Yards | 21,872.27 | yd |
| Miles | 12.427424 | mi |
| Nautical miles | 10.799136 | nmi |
km to mm at a glance
| Kilometres | Millimetres |
|---|---|
| 1 km | 1,000,000 mm |
| 2 km | 2,000,000 mm |
| 3 km | 3,000,000 mm |
| 5 km | 5,000,000 mm |
| 10 km | 10,000,000 mm |
| 20 km | 20,000,000 mm |
| 25 km | 25,000,000 mm |
| 50 km | 50,000,000 mm |
| 100 km | 100,000,000 mm |
| 250 km | 250,000,000 mm |
| 500 km | 500,000,000 mm |
| 1,000 km | 1,000,000,000 mm |
How to convert kilometres to millimetres
Multiply by 1,000,000 — one kilometre is 1,000,000 millimetres. That factor is exact: it comes from the definition of the units rather than from a measurement, so it will not change and does not need rounding.
Working 20 × 1,000,000 = 20,000,000
In words: twenty million millimetres.
What these units are
The kilometre and the millimetre are covered in the length unit guide, along with every other unit on this page.
Questions
How many millimetres are in a kilometre?
One kilometre is 1,000,000 millimetres. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 20 kilometres in millimetres?
20 kilometres is 20,000,000 millimetres. The working is 20 × 1,000,000 = 20,000,000.
Is an inch exactly 2.54 centimetres?
Yes, exactly. Since 1959 the international inch has been defined as 25.4 millimetres, so the figure is a definition rather than a measurement. Every foot, yard and mile figure on this page follows from it and is equally exact.
Why is a nautical mile different from a mile?
It is tied to the Earth rather than to a body part. One nautical mile is one minute of latitude, fixed at exactly 1,852 metres, which makes chart work straightforward for anyone navigating by degrees.
How do I write my height in metric?
Convert the whole thing to inches first, then multiply by 2.54. Five foot ten is 70 inches, which is 177.8 cm. Converting the feet and the inches separately is where the arithmetic usually goes wrong.
Meter or metre?
Both name the same unit. "Metre" is the international spelling used by the SI and most English-speaking countries; "meter" is standard in the United States. Either spelling will find this page.