Convert MCM to Cubic Kilometres (MCM to km3)
1 million cubic metres (MCM) = 0.001 cubic kilometres (km³). 1 km³ = 1000 MCM. Example: 15 MCM = 15 × 0.001 = 0.015 km³.
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1 MCM = 0.001 km³
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk MCM to cubic kilometre converter to paste a column from Excel.
How to Convert MCM to Cubic Kilometre
- 1 MCM = 0.001 km³
- 1 km³ = 1000 MCM
- Example: convert 15 MCM to km³: 15 MCM = 15 × 0.001 km³ = 0.015 km³
Formula
km³ = MCM ÷ 1000
Derivation from SI units:
- 1 MCM = 10⁶ m³ = 1 hm³ (cubic hectometre).
- 1 km³ = 10⁹ m³ = 1 BCM.
Both units are defined exactly, so the factor is exact. MCM definition: million cubic metres; Cubic Kilometre definition: cubic kilometre.
Worked examples
- A reading of 5 MCM converts to 0.005 km³.
5 MCM × 0.001 = 0.005 km³ - A value of 100 MCM is 0.1 km³.
100 MCM × 0.001 = 0.1 km³
MCM to Cubic Kilometre conversion table
| MCM | Cubic Kilometres (km³) |
|---|---|
| 0.1 MCM | 0.0001 km³ |
| 0.5 MCM | 0.0005 km³ |
| 1 MCM | 0.001 km³ |
| 5 MCM | 0.005 km³ |
| 10 MCM | 0.01 km³ |
| 50 MCM | 0.05 km³ |
| 100 MCM | 0.1 km³ |
| 500 MCM | 0.5 km³ |
| 1000 MCM | 1 km³ |
| 10000 MCM | 10 km³ |
Where it's used
MCM are used for CWC weekly reservoir storage bulletins, while cubic kilometres appear in global water budgets. Both measure volume of stored or released water (reservoirs, river flows, allocations), so the conversion is a fixed factor.
MCM to other water volume units
| Conversion | 1 MCM equals |
|---|---|
| MCM to cubic kilometre | 0.001 km³ |
| MCM to BCM | 0.001 BCM |
| MCM to TMC | 0.03531466672 TMC |
| MCM to acre-foot | 810.7131938 acre-ft |
| MCM to cubic metre | 1000000 m³ |
| MCM to Mcft | 35.31466672 Mcft |
| MCM to MAF | 0.0008107131938 MAF |
| MCM to hectare-metre | 100 ha·m |
Show 2 more units
| MCM to megalitre | 1000 ML |
|---|---|
| MCM to gigalitre | 1 GL |
Frequently asked questions
How many cubic kilometres are in 1 million cubic metres?
1 MCM = 0.001 km³.
How do I convert million cubic metres to cubic kilometres?
Multiply the value in MCM by 0.001, or divide it by 1000. For example, 15 MCM × 0.001 = 0.015 km³.
Is the MCM to km³ conversion exact?
Yes. Both units are defined exactly, and 1 MCM is exactly 0.001 km³.
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 MCM to Cubic Kilometres (MCM to km3). Retrieved October 29, 2026, from https://scientificconverters.com/water-volume/mcm-to-cubic-kilometers/
IEEE
Scientific Converters, "Convert MCM to Cubic Kilometres (MCM to km3)," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/water-volume/mcm-to-cubic-kilometers/