How Many Units Fit in a Shipping Container? A Simple CBM Guide

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"How many units fit in a container?" is one of the questions we hear most.

The honest answer is: it depends on your carton, not your product. Two factories can make the same product and pack it so differently that one fits 30% more into the same container.

Here's how to work it out yourself, in five minutes, with a calculator.

The three containers you'll hear about

Container	Inside size (approx.)	Total volume	Realistic to fill
20ft (20GP)	5.9 × 2.35 × 2.39 m	about 33 CBM	about 25–28 CBM
40ft (40GP)	12.0 × 2.35 × 2.39 m	about 67 CBM	about 55–58 CBM
40ft high cube (40HQ)	12.0 × 2.35 × 2.69 m	about 76 CBM	about 65–68 CBM

Why can't you fill 100%? Because cartons are boxes, not liquid. There are always gaps at the top, sides and door. Sizes also vary a little between container owners. Plan with the "realistic" column.

Good to know: a 40ft container costs much less than two 20ft containers, and the high cube gives you about 30cm more height for a small extra cost. For light, bulky goods, the 40HQ is often the best value.

Step 1: Work out CBM per carton

CBM means cubic metre. Measure your outer carton in metres and multiply:

Length × Width × Height = CBM per carton

Example: a carton of 60 × 40 × 40 cm

0.60 × 0.40 × 0.40 = 0.096 CBM

Step 2: How many cartons fit?

Divide the realistic space by your carton CBM.

20ft: 28 ÷ 0.096 ≈ 290 cartons
40HQ: 68 ÷ 0.096 ≈ 700 cartons

Step 3: How many units?

Multiply by the units per carton. Say 24 units per carton:

20ft: 290 × 24 ≈ 7,000 units
40HQ: 700 × 24 ≈ 16,800 units

That's your rough number. Your forwarder or factory can make an exact loading plan once the carton size is final.

Don't forget weight

Volume isn't the only limit. Heavy products (tiles, metal parts, liquids, books) can hit the weight limit before the container is full.

• Containers have a maximum payload, but the road limits at both ends are often lower
• Trucks, ports and countries all have their own rules
• For heavy goods, ask your forwarder for the real maximum weight for your route

For heavy goods, a 20ft container is often the better choice. It fills up by weight anyway.

Pallets or loose cartons?

• Loose cartons ("floor loaded"): fit the most. Loading and unloading take longer
• Pallets: faster to unload and often required by warehouses and big retailers. But pallets take space, often around 10–20% less product per container

Ask your warehouse what they need before the factory packs.

The carton is where you save money

This is the part most founders miss. Small changes to the carton can make a big difference:

• Make the carton a few centimetres smaller. Less empty space, more cartons per container
• Change units per carton. 24 or 30 per carton can fill space better than 20
• Pack smarter. Nest products, fold inserts, rotate items
• Check the carton is strong enough to be stacked to the top of the container. The bottom row carries everything

Example: if the carton above could shrink to 55 × 40 × 40 cm (0.088 CBM), the 20ft count goes from about 290 to about 318 cartons. That's around 670 more units in the same container, for the same freight price.

Ask the factory for these numbers early

Before production, ask for:

1. Units per carton
2. Outer carton size (L × W × H in cm)
3. Gross weight per carton (kg)
4. A photo of a packed sample carton

With these four numbers, you can plan your container, your freight cost and your cost per unit, before a single unit is made.

The bottom line

How many units fit in a container comes down to simple math: CBM per carton, realistic container space, units per carton. Do it early, ask about weight, and treat your carton as part of your product. It's one of the cheapest ways to lower your cost per unit.

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