Convert Cubic Kilometres to MCM (km3 to MCM)
1 cubic kilometre (km³) = 1000 million cubic metres (MCM). 1 MCM = 0.001 km³. Example: 15 km³ = 15 × 1000 = 15000 MCM.
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1 km³ = 1000 MCM
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk cubic kilometre to MCM converter to paste a column from Excel.
How to Convert Cubic Kilometre to MCM
- 1 km³ = 1000 MCM
- 1 MCM = 0.001 km³
- Example: convert 15 km³ to MCM: 15 km³ = 15 × 1000 MCM = 15000 MCM
Formula
MCM = km³ × 1000
Derivation from SI units:
- 1 km³ = 10⁹ m³ = 1 BCM.
- 1 MCM = 10⁶ m³ = 1 hm³ (cubic hectometre).
Both units are defined exactly, so the factor is exact. Cubic Kilometre definition: cubic kilometre; MCM definition: million cubic metres.
Worked examples
- A reading of 10 km³ converts to 10000 MCM.
10 km³ × 1000 = 10000 MCM - A value of 500 km³ is 500000 MCM.
500 km³ × 1000 = 500000 MCM
Cubic Kilometre to MCM conversion table
| Cubic Kilometres (km³) | MCM |
|---|---|
| 0.1 km³ | 100 MCM |
| 1 km³ | 1000 MCM |
| 5 km³ | 5000 MCM |
| 10 km³ | 10000 MCM |
| 50 km³ | 50000 MCM |
| 100 km³ | 100000 MCM |
| 500 km³ | 500000 MCM |
| 1000 km³ | 1000000 MCM |
| 4000 km³ | 4000000 MCM |
| 10000 km³ | 10000000 MCM |
Where it's used
Cubic Kilometres are used for global water budgets, while million cubic metres appear in CWC weekly reservoir storage bulletins. Both measure volume of stored or released water (reservoirs, river flows, allocations), so the conversion is a fixed factor.
Cubic Kilometre to other water volume units
| Conversion | 1 km³ equals |
|---|---|
| cubic kilometre to MCM | 1000 MCM |
| cubic kilometre to BCM | 1 BCM |
| cubic kilometre to TMC | 35.31466672 TMC |
| cubic kilometre to acre-foot | 810713.1938 acre-ft |
| cubic kilometre to cubic metre | 1000000000 m³ |
| cubic kilometre to Mcft | 35314.66672 Mcft |
| cubic kilometre to MAF | 0.8107131938 MAF |
| cubic kilometre to hectare-metre | 100000 ha·m |
Show 2 more units
| cubic kilometre to megalitre | 1000000 ML |
|---|---|
| cubic kilometre to gigalitre | 1000 GL |
Frequently asked questions
How many million cubic metres are in 1 cubic kilometre?
1 km³ = 1000 MCM.
How do I convert cubic kilometres to million cubic metres?
Multiply the value in km³ by 1000. For example, 15 km³ × 1000 = 15000 MCM.
Is the km³ to MCM conversion exact?
Yes. Both units are defined exactly, and 1 km³ is exactly 1000 MCM.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4 (derived units) and Table 8 (non-SI units accepted for use with the SI).
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Cubic Kilometres to MCM (km3 to MCM). Retrieved October 29, 2026, from https://scientificconverters.com/water-volume/cubic-kilometers-to-mcm/
IEEE
Scientific Converters, "Convert Cubic Kilometres to MCM (km3 to MCM)," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/water-volume/cubic-kilometers-to-mcm/