CBM Calculator: Cubic Meters & How Many Boxes Fit a Container

By Owen Hartley, Editor · Last updated November 11, 2026

Enter each carton size with its quantity and weight. The calculator adds up cubic meters and cubic feet, then shows how many cartons of one size fit in each container type and whether weight or space runs out first.

How to calculate CBM

CBM means cubic meters. Multiply length, width and height in meters, then multiply by the number of cartons. With centimeters, divide the product by 1,000,000; with inches, multiply cubic inches by 0.000016387064. Ten cartons of 50 × 40 × 30 cm come to 0.6 cubic meters, or 21.19 cubic feet.

Measure each carton at its widest points, including bulges and handles. For palletized freight, measure the whole pallet as one unit: a 1.2 × 0.8 × 1.5 m pallet is 1.44 cubic meters no matter how full the cartons inside are. Ocean and air carriers bill on the outside size, not on how much product is inside.

Converting CBM to cubic feet and back

One cubic meter is 35.315 cubic feet, and one cubic foot is 0.028317 cubic meters. Both numbers come from the exact definition of the foot as 0.3048 meters. A cubic foot is also 1,728 cubic inches, which is the divisor US carriers use when you measure in inches.

Calculated from the definition 1 inch = 25.4 mm

Pick one unit at the top of the calculator and enter every line in it; the calculator converts everything to millimeters before doing any math. Results are shown in both cubic meters and cubic feet, rounded to two decimals for display, and totals are added up before any rounding.

How many boxes fit in a 20 ft or 40 ft container

The calculator tries all six ways to turn one carton and counts how many fit in a straight grid. By default it uses the smallest inside dimensions published by Maersk, Hapag-Lloyd and CMA CGM. Cartons of 60 × 40 × 40 cm fit 225 times in a 20 ft box, filling 65 percent of its volume.

Calculated from: Maersk, Our fleet - equipment specifications: dry containers (PDF, maersk.com local information); Maersk, Our fleet - equipment specifications: reefer containers (PDF, maersk.com local information); Hapag-Lloyd, Container Specification (booklet, 03/2016), pp. 9, 11, 13, 15, 41, 43; CMA CGM, Containers - technical specifications (web page), checked Oct 30, 2026

The count is an upper limit for identical cartons only. Real loads usually take fewer: pallets, dunnage, bracing and the space a forklift or a person needs all cost room. A smarter mixed pattern can sometimes fit a few more cartons than a straight grid. You can pick one carrier's container instead of the smallest-of-three default.

Weight limit vs volume limit

Dense cargo runs out of payload before it runs out of space. Cases of 40 × 30 × 20 cm at 60 kg each fit 1,078 times in a 20 ft container by size, but 28,200 kg of payload allows only 470 of them. The calculator compares both limits and tells you which one stops the load.

The payload limit it uses is the lowest among the three carriers for that type, unless you choose a carrier: 28,200 kg for a 20 ft dry, 26,760 kg for a 40 ft dry and 26,580 kg for a 40 ft high cube. Where a carrier's printed payload is higher than its maximum gross weight minus its tare, the calculator uses the lower number. Road and rail weight limits at either end can be lower than the container's rating; they are not part of this calculation.

Units, rounding and container data used

All lengths are converted to millimeters with 1 inch = 25.4 mm. Volume is length × width × height × quantity; cubic feet use 1 ft = 0.3048 m exactly. Container fit divides each inside dimension by the matching carton side, rounds down, and multiplies; the best of six orientations wins.

Container dimensions and payloads are read from the same carrier data shown on the container dimensions page. Ten test cases, including unit conversions, a carton that fits only one way and a carton too large for any container, run on every build; if one fails, the page is not published.