Container Loading Calculator

How the container loading calculator works

For one carton size, the tool works out the most cartons that fit inside the container's internal dimensions, then checks that number against the payload. Whichever limit you hit first is the real capacity.

• Space. It tries every way the carton can face (or only the upright ones if you tick "this side up") and also layouts made of two blocks: for example rows lengthwise, then the remaining width filled with cartons turned 90°. That is how loaders use the gap a single grid leaves.
• Payload. The container's rated payload divided by carton weight gives a second limit. If your truck or rail leg has a lower limit, enter it as the payload cap.
• Quantity. If you enter the number of cartons to ship, it reports how many containers that takes and what is left over.

The result is a planning figure. Real loads lose some space to dunnage, airbags, bracing and the clearance needed to close the doors, so plan for a few per cent less on tight loads, and get a load plan from your forwarder for anything fragile or heavy.

Container dimensions and weight limits

These are representative steel dry containers from the large carrier fleets. Individual boxes vary by a few millimetres inside and by a few hundred kilograms in tare and rated gross weight; the CSC safety plate on the door is the authority for any one container. Door openings are smaller than the interior, which matters for tall cargo: a standard box has about 2,280 mm of door height against 2,393 mm inside.

The arithmetic

⌊ ⌋ means round down: a fraction of a carton does not load.

Worked example: why turning cartons matters

A supplier packs into 60 × 40 × 40 cm cartons at 12 kg each and has 600 cartons ready. In a 20′ box (5,898 × 2,352 × 2,393 mm):

• Lengthwise in a single grid: 9 along the length (5,400 mm), 5 across (2,000 mm), 5 high (2,000 mm) = 225 cartons, with 352 mm of width wasted down the whole box.
• Better: one row of cartons turned with the 40 cm side across uses 400 mm of width and takes 9 × 1 × 5 = 45. The remaining 1,952 mm of width takes three cartons on their 60 cm side, 14 along the length: 14 × 3 × 5 = 210. Total 255 cartons, 13 % more than the simple grid.
• Weight: 255 × 12 kg = 3,060 kg, far under the payload. Space is the limit, and 600 cartons need three 20′ containers, or one 40′ high cube, which the comparison table shows takes all 600.

Mistakes that leave cargo on the dock or cost fines

• Loading to the rated payload when the truck can't carry it. In the US, the 80,000 lb federal gross vehicle limit usually leaves room for roughly 44,000 lb (about 20 t) of cargo in a container on a standard chassis without an overweight permit. European and UK limits (typically 40 to 44 t gross) differ again. Enter the road limit as the payload cap.
• Declaring the wrong gross mass. Under SOLAS, the shipper must provide a verified gross mass (VGM) for every packed container before it is loaded on the ship. Weigh it, don't estimate it.
• Ignoring the door. A carton or crate taller than the door opening will not go in even if the interior is tall enough.
• Uneven weight. Heavy cargo should be spread along the floor with the centre of gravity near the middle of the box, not stacked at the doors.
• Tipping cartons marked this side up. Tick the option so the layout only spins cartons on the floor.