# CBM calculator

CBM = length × width × height (in metres) × number of cartons. 50 cartons of 40 × 30 × 20 cm = 50 × 0.024 = 1.2 m³ (42.38 ft³), about 3.6 % of a 20GP.

Interactive calculator: https://cartonmath.com/cbm-calculator/
URL parameters: unit=cm|mm|in, wu=kg|lb, l, w, h, qty, wt (single line) or rows=LxWxHxQTYxWT,LxWxHxQTYxWT (several lines).

## Worked example

1. One carton: 0.40 × 0.30 × 0.20 m = 0.024 m³
2. 50 cartons: 50 × 0.024 = 1.2 m³
3. Cubic feet: 1.2 × 35.315 = 42.38 ft³
4. Air chargeable, 1:6000: 1.2 × 166.67 = 200 kg; actual 600 kg, so 600 kg
5. Sea LCL, W/M: max(1.2 m³, 0.6 t) = 1.2 revenue tons
6. Share of a 20GP: 1.2 ÷ 33.2 = 3.6 %

## Container capacity

| Container | Capacity (m3) | Practical 80-90 % (m3) |
|---|---|---|
| 20GP | 33.2 | 26.6-29.9 |
| 40GP | 67.7 | 54.2-60.9 |
| 40HQ | 76.4 | 61.1-68.7 |
| 45HQ | 86 | 68.8-77.4 |

## FAQ

**How do I calculate CBM?**
Multiply length × width × height in metres, then by the number of cartons. A 40 × 30 × 20 cm carton is 0.4 × 0.3 × 0.2 = 0.024 m³, so 50 of them are 1.2 CBM. From centimetres you can also divide L × W × H by 1,000,000.

**How many CBM fit in a 20ft container?**
A typical 20GP has about 33.2 m³ inside, but mixed cartons usually load to 80–90 % of that, roughly 27 to 30 m³. A 40GP holds about 67.7 m³ and a 40HQ about 76.4 m³.

**What is W/M in LCL shipping?**
Weight or measure: the LCL rate is charged per revenue ton, which is the greater of the volume in cubic metres and the weight in metric tons. 1.2 m³ weighing 600 kg pays for 1.2 revenue tons; 1.2 m³ weighing 2,000 kg pays for 2.

**How is air freight chargeable weight worked out from CBM?**
At the common 1:6000 ratio, one cubic metre counts as 166.67 kg. Multiply the CBM by 166.67 and compare it with the actual gross weight; the airline charges the higher figure. Check your forwarder's ratio.

**How many cubic feet is one CBM?**
One cubic metre is 35.315 cubic feet. One cubic foot is 0.0283 m³.

Source page: https://cartonmath.com/cbm-calculator/
Updated: 2026-10-06
Publisher: CartonMath (https://cartonmath.com)