How to convert square kilometers to square millimeters
mm² = km² × 1,000,000,000,000Multiply the value in square kilometers by 1,000,000,000,000. To go the other way, multiply by 1×10⁻¹² (or divide by 1,000,000,000,000).
A square kilometer is larger than a square millimeter: one square kilometer contains 1,000,000,000,000 square millimeters.
Worked examples
- 1 square kilometer1 km² × 1,000,000,000,000 = 1,000,000,000,000 mm²
- 5 square kilometers5 km² × 1,000,000,000,000 = 5,000,000,000,000 mm²
- 10 square kilometers10 km² × 1,000,000,000,000 = 10,000,000,000,000 mm²
- 20 square kilometers20 km² × 1,000,000,000,000 = 20,000,000,000,000 mm²
- 100 square kilometers100 km² × 1,000,000,000,000 = 100,000,000,000,000 mm²
Square kilometers to square millimeters conversion table
Values are calculated by the conversion engine and rounded to 8 significant figures.
| Square kilometers (km²) | Square millimeters (mm²) |
|---|---|
| 0.1 km² | 100,000,000,000 mm² |
| 0.25 km² | 250,000,000,000 mm² |
| 0.5 km² | 500,000,000,000 mm² |
| 1 km² | 1,000,000,000,000 mm² |
| 2 km² | 2,000,000,000,000 mm² |
| 3 km² | 3,000,000,000,000 mm² |
| 4 km² | 4,000,000,000,000 mm² |
| 5 km² | 5,000,000,000,000 mm² |
| 6 km² | 6,000,000,000,000 mm² |
| 7 km² | 7,000,000,000,000 mm² |
| 8 km² | 8,000,000,000,000 mm² |
| 9 km² | 9,000,000,000,000 mm² |
| 10 km² | 10,000,000,000,000 mm² |
| Square kilometers (km²) | Square millimeters (mm²) |
|---|---|
| 12 km² | 12,000,000,000,000 mm² |
| 15 km² | 15,000,000,000,000 mm² |
| 20 km² | 20,000,000,000,000 mm² |
| 25 km² | 25,000,000,000,000 mm² |
| 30 km² | 30,000,000,000,000 mm² |
| 40 km² | 40,000,000,000,000 mm² |
| 50 km² | 50,000,000,000,000 mm² |
| 75 km² | 75,000,000,000,000 mm² |
| 100 km² | 100,000,000,000,000 mm² |
| 250 km² | 250,000,000,000,000 mm² |
| 500 km² | 500,000,000,000,000 mm² |
| 1,000 km² | 1×10¹⁵ mm² |
About the units
Square kilometer (km²)
One million square metres or 100 hectares; used for city, lake and country areas. One square kilometer equals 1,000,000 square meters (m²).
Square millimeter (mm²)
Used for wire cross-sections in metric countries (e.g. 2.5 mm² cable). One square millimeter equals 0.000001 square meters (m²).
Frequently asked questions
How many square millimeters are in one square kilometer?
There are 1,000,000,000,000 square millimeters in one square kilometer, and this value is exact by definition.
How do I convert square kilometers to square millimeters?
Multiply the number of square kilometers by 1,000,000,000,000. For example, 10 km² × 1,000,000,000,000 = 10,000,000,000,000 mm².
How many square kilometers are in one square millimeter?
One square millimeter equals 1×10⁻¹² square kilometers. That is the reverse factor, 1 ÷ 1,000,000,000,000.
What is 10 square kilometers in square millimeters?
10 km² = 10,000,000,000,000 mm².
Is this km² to mm² converter accurate?
Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.
Convert square kilometers to other units
- Square kilometers to square feet
- Square kilometers to square meters
- Square kilometers to acres
- Square kilometers to hectares
- Square kilometers to square miles
- Square kilometers to square centimeters
- Square kilometers to square inches
- Square kilometers to square yards