Short answer: a 40ft standard (40GP) has about 67.4 m³ of internal volume; a 40ft high cube (40HC) has about 75.9 m³. Divide that by your carton volume and you get a theoretical maximum — then take 10–25% off for real-world packing loss.
The numbers you actually need
Container capacity is always quoted as internal dimensions, because that is what your cargo touches. Never plan against external size.
| Container | Internal L × W × H | Volume | Max payload |
|---|---|---|---|
| 20GP | 5.89 × 2.35 × 2.39 m | 33.1 m³ | ~28,200 kg |
| 40GP | 12.00 × 2.35 × 2.39 m | 67.4 m³ | ~28,800 kg |
| 40HC | 12.00 × 2.35 × 2.69 m | 75.9 m³ | ~28,600 kg |
| 45HC | 13.51 × 2.35 × 2.69 m | 85.4 m³ | ~29,100 kg |
| 53’ domestic | 16.15 × 2.59 × 2.74 m | 114.6 m³ | ~27,200 kg |
Nominal internal dimensions. Actual containers vary by a few centimetres between makers — always confirm with the line, or enter your own dimensions in the calculator.
Step 1 — The volume method (fast, optimistic)
Take one carton and multiply length × width × height in metres. Then divide the container volume by it.
Example: carton 60 × 40 × 40 cm = 0.096 m³.
40HC: 75.9 ÷ 0.096 = 791 cartons.
That number is a ceiling, not a plan. It assumes zero gaps, zero pallets and perfect stacking — none of which survive contact with a loading dock.
Step 2 — The grid method (what actually ships)
Divide each container dimension by the matching carton dimension and round down:
- Length: 12.00 ÷ 0.60 = 20 cartons
- Width: 2.35 ÷ 0.40 = 5 cartons (35 cm left over)
- Height: 2.69 ÷ 0.40 = 6 cartons (29 cm left over)
20 × 5 × 6 = 600 cartons, or 57.6 m³ — only 76% of the box. The leftovers are real: you cannot fold 35 cm of air into a carton.
Try rotating the carton so the 60 cm side runs across the container: 12.00 ÷ 0.40 = 30, 2.35 ÷ 0.60 = 3, 2.69 ÷ 0.40 = 6 → 540 cartons. Worse. Orientation matters more than volume.
Step 3 — Recover the waste
This is where planning beats arithmetic. A good loading plan mixes orientations, fills the leftover strip with a second carton size, and stacks to the roof where the weight allows. On the same 40HC, a mixed 3-size plan reaches 716 cartons at 93% space used — roughly 19% more cargo than the single-orientation grid, on the same freight bill.
When weight runs out before space
Volume is only half the story. A 40HC is capped around 28,600 kg. If each carton weighs 45 kg, 600 cartons is 27,000 kg — you are at the weight limit with a quarter of the box still empty. Dense cargo (tiles, hardware, liquids) hits this constantly.
The rule of thumb: below roughly 380 kg/m³ you run out of space first; above it you run out of weight first. Check both before you quote.
Pallets change everything
If the cargo is palletised, you are no longer counting cartons — you are counting pallet positions. A standard 1200 × 1000 mm pallet gives you 20–21 positions in a 40ft container when single-stacked, and up to 40 when double-stacked and weight permits. Each position holds whatever fits on the pallet footprint and under the height limit.
Do it in three clicks instead
All of the above is arithmetic you should not be doing by hand at 6pm before a cut-off. Quick Loading takes your carton sizes — typed in, or imported from an Excel SKU list — and returns a real 3D plan with space used, weight used and every pallet accounted for.
Try it on your own cartons
Free, no account, no install. Nine vehicle types, six languages.
Open the calculator →Frequently asked
How many cartons fit in a 20ft container?
About half a 40ft: 33 m³ of internal volume, so roughly 300–360 cartons of the same 60 × 40 × 40 cm size, depending on orientation and stacking.
Is a 40HC worth it over a 40GP?
If your cargo is light and stackable, yes — the high cube adds 8.6 m³ (about 13%) for a small premium. If you are weight-limited, the extra height buys you nothing.
How much space does a pallet waste?
Palletising typically costs 5–12% of the container, mostly from the gaps between pallets and the unusable strip along the walls. A plan that respects the real gaps recovers most of it.
Can I load more than 28,800 kg in a 40ft?
Not legally on the road in most jurisdictions. The container may be rated higher, but road weight limits usually bind first — check the rules for every country your cargo crosses.