Math & Science
Cubic Meter Calculator
Work out shipment volume in cubic metres, and see whether you will be charged on volume or on weight.
Cubic Meter Calculator
About the Cubic Meter Calculator
CBM — cubic metres — is how freight gets measured and, very often, how it gets billed. This calculator works out the volume of your shipment from its dimensions, multiplies by the number of cartons, and shows the total in cubic metres, litres and cubic feet.
It also calculates volumetric weight, which is where shipping costs surprise people. Carriers charge on whichever is greater: actual weight or volumetric weight. A carton of pillows is light but bulky, so it gets billed on the space it occupies rather than what it weighs.
Enter dimensions in metres, centimetres, millimetres, inches, feet or yards. Everything converts internally, so you can work straight from a packing list in whatever units it happens to use.
How to use the Cubic Meter Calculator
- Enter the dimensions of one package and pick the unit.
- Enter how many packages you are shipping.
- Optionally add the weight per package.
- Pick the volumetric divisor your carrier uses.
- Select Calculate CBM to see which basis you will be billed on.
The formula
CBM = length × width × height (all in metres)
Total CBM = CBM per carton × number of cartons
Worked example
50 cartons, each 60 cm × 40 cm × 35 cm, weighing 12 kg each.
Convert to metres: 0.6 × 0.4 × 0.35 = 0.084 m³ per carton.
Total volume: 0.084 × 50 = 4.2 CBM.
Actual weight: 12 × 50 = 600 kg.
Volumetric weight (air, ÷ 6000): (60 × 40 × 35) ÷ 6000 = 14 kg per carton, so 700 kg.
4.2 CBM — billed at 700 kg, not 600 kg
The volumetric figure wins, so you pay for 100 kg of air.
How volumetric weight works
Aircraft and lorries run out of space long before they run out of weight capacity. Volumetric weight lets carriers charge for the room a shipment takes up, converting volume into a notional weight using a fixed divisor.
Volumetric weight (kg) = (L × W × H in cm) ÷ divisor
Chargeable weight = whichever is greater, actual or volumetric.
Which divisor applies
| Mode | Divisor | Equivalent density |
|---|---|---|
| Air freight (IATA standard) | 6000 | 167 kg per CBM |
| Air express couriers | 5000 | 200 kg per CBM |
| Some domestic couriers | 4000 | 250 kg per CBM |
| Road / LTL freight | 3000 | 333 kg per CBM |
| Sea LCL | 1 CBM = 1,000 kg | 1,000 kg per CBM |
A smaller divisor gives a larger volumetric weight, so it costs you more. Express couriers commonly use 5000 while standard air freight uses 6000 — on the same carton that is a 20% difference in chargeable weight. Always check the divisor in your carrier's tariff rather than assuming.
Sea freight works differently. LCL shipments are quoted per "revenue tonne", meaning whichever is greater of one cubic metre or one tonne. Cargo lighter than 1,000 kg per CBM is billed on volume.
Container capacities
| Container | Internal volume | Realistic load | Max payload |
|---|---|---|---|
| 20 ft standard | 33.2 CBM | 25–28 CBM | ~28,200 kg |
| 40 ft standard | 67.7 CBM | 55–58 CBM | ~26,500 kg |
| 40 ft high cube | 76.4 CBM | 60–68 CBM | ~26,500 kg |
| 45 ft high cube | 86.1 CBM | 72–78 CBM | ~27,600 kg |
Never plan to the theoretical figure. Cartons do not tessellate perfectly, pallets waste height, and load stability needs gaps. Working to about 85% of internal volume is the usual planning rule, which is why a 20 ft container holds around 25–28 CBM in practice rather than 33.
CBM and cubic feet
- 1 CBM = 35.3147 cubic feet.
- 1 cubic foot = 0.0283168 CBM.
- 1 CBM = 1,000 litres.
To convert CFT to CBM, divide by 35.3147. Freight quotes in Asia and Europe generally use CBM; US domestic quotes often use cubic feet, so check which unit a rate refers to before comparing.
Cutting your shipping cost
- Shrink the box. Volumetric weight scales with all three dimensions, so trimming a few centimetres everywhere helps disproportionately.
- Watch the tipping point. If actual weight already exceeds volumetric, a bigger box costs nothing extra. Below it, every centimetre counts.
- Consolidate. One large carton usually has less wasted space than several small ones.
- Compare divisors. For bulky, light goods the divisor matters more than the headline rate.
For tank and vessel capacity rather than shipment volume, see the tank area calculator or the general volume calculator.
CBM formula for any unit
CBM means cubic metres. Multiply length × width × height, then convert to cubic metres:
| Measured in | CBM formula | Example |
|---|---|---|
| Centimetres | L × W × H ÷ 1,000,000 | 60 × 40 × 50 cm = 0.12 m³ |
| Millimetres | L × W × H ÷ 1,000,000,000 | 600 × 400 × 500 mm = 0.12 m³ |
| Inches | L × W × H ÷ 61,024 | 24 × 16 × 20 in = 0.126 m³ |
| Feet | L × W × H ÷ 35.315 | 2 × 2 × 2 ft = 0.227 m³ |
Convert CFT to m3: cubic feet to CBM and back
- 1 CBM = 35.315 cubic feet. Multiply CBM by 35.315 to get CFT.
- 1 cubic foot = 0.0283 CBM. Divide CFT by 35.315 to get CBM.
So a 20 ft container's roughly 33 CBM of space is about 1,165 cubic feet.
CFM to m³/h (air flow)
Fans and ducts use flow rates rather than volumes. 1 CFM (cubic foot per minute) equals 1.699 m³/h. A 100 CFM extractor fan moves about 170 m³ of air an hour. To go back, divide m³/h by 1.699.
Other ways to use this calculator
Volume and flow conversions live here too.
- CFT to m³ converter — divide cubic feet by 35.315.
- CFM to m³/hr converter — multiply CFM by 1.699.
- CBM calculator for shipping cartons — enter carton size and count for total CBM and volumetric weight.
- Shipping volume and freight calculator — CBM is the volume freight companies charge by.
- Carton CBM — calculate CBM from cm: length × width × height in cm ÷ 1,000,000, times the number of cartons.
- CFM to m3 hr — 1 CFM is about 1.699 m³ per hour; see the air flow section above.
Related guides
Frequently asked questions
CBM stands for cubic metre, the standard volume measure in freight. Multiply length × width × height in metres for one carton, then multiply by the number of cartons. Fifty cartons of 60 × 40 × 35 cm give 0.084 CBM each, or 4.2 CBM in total. Shipping quotes, container planning and LCL sea freight rates are all built around this figure.
Volumetric weight converts the space a shipment occupies into a notional weight, so carriers can charge for bulky but light goods. Multiply the dimensions in centimetres and divide by the carrier's divisor — usually 5000 or 6000 for air. You are billed on whichever is greater, actual or volumetric. A carton of pillows almost always gets charged on volume.
Whichever your carrier specifies — check the tariff rather than assuming. IATA standard air freight uses 6000, while express couriers such as DHL, FedEx and UPS commonly use 5000. Some domestic road services use 4000 or even 3000. A smaller divisor produces a larger chargeable weight, so 5000 costs about 20% more than 6000 on the same carton.
A 20 ft standard container has about 33.2 CBM of internal space, but 25–28 CBM is the realistic load. Cartons do not stack perfectly, pallets waste height, and stable loading needs gaps, so planners work to roughly 85% of the theoretical volume. A 40 ft standard holds around 55–58 CBM of its 67.7, and a 40 ft high cube around 60–68.
Multiply length, width and height in centimetres, then divide by 1,000,000. A 60 × 40 × 50 cm carton is 120,000 ÷ 1,000,000 = 0.12 CBM. Multiply by the number of cartons for the total.
One cubic metre equals 35.315 cubic feet. To convert CBM to CFT, multiply by 35.315. To convert cubic feet to CBM, divide by 35.315.
Sources and further reading
- IATA — Air cargo standards — the 6000 volumetric divisor for air freight
- NIST — Guide for the Use of the International System of Units — cubic metre definition and volume conversions
- ISO 668 — Series 1 freight containers — standard container dimensions and capacities