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How to Calculate CBM and Plan a Container Load

Work out how much space and weight your cartons take, and how many containers a clothing shipment needs.

By Apparel Search · Updated October 2026

Freight is priced by space and weight, so knowing both before you ship helps you budget, pick the right way to ship and avoid surprises at the port. This guide shows how to measure cartons, calculate cubic meters (CBM) and chargeable weight, and estimate container needs for mixed garment cartons. Your freight forwarder makes the final load plan, so treat these numbers as a planning estimate.

Do the math as you read

Use the free Carton & Container Load Calculator to total mixed cartons and see how they load.

1. Measure and weigh your packed cartons

Measure the outside length, width and height of each packed carton, and weigh it with the garments inside. Use the same unit for every measurement. If you have more than one carton size, such as a smaller carton for small sizes and a bigger one for 3XL, record each size and how many of each you have.

2. Calculate CBM

CBM means cubic meters. For one carton, multiply length x width x height in meters. A carton of 60 x 40 x 38 cm is 0.60 x 0.40 x 0.38 = 0.0912 CBM, so 40 of them are about 3.65 CBM. For a shipment, calculate each carton size separately and add them up.

3. Work out chargeable weight

Carriers charge for the greater of actual weight and volumetric weight, so bulky but light cargo, which is common with garments, still pays for its space. For air freight, volumetric weight is commonly length x width x height in centimeters divided by 6,000 (some carriers use a different divisor). A 60 x 40 x 38 cm carton works out to 15.2 kg, even if it weighs 14 kg. For LCL sea freight, charges are commonly based on the greater of cubic meters or tonnes. Confirm the basis with your forwarder.

4. Choose FCL, LCL or air

FCL (full container load) means you book a whole container. LCL (less than container load) means your cartons share a container with other shippers, which suits small shipments. Air is faster and costs more. As a rough guide, a 20-foot container holds about 33 CBM inside, a 40-foot about 67 CBM and a 40-foot high cube about 76 CBM, but sizes and payload limits vary by carrier, so check yours.

5. Choose floor loading or pallets

Floor loaded cartons are stacked directly in the container, which usually fits more cartons but takes more labor to load and unload. Palletized cartons are quicker to handle and are often required by retailers and distribution centers, but pallets take up space and weight. Ask your customer and your forwarder which method you need.

6. Estimate how many containers you need

Divide your total CBM by the container's inside volume for the best case. Real loads never fill a container completely, because of gaps, uneven carton heights and weight limits, so the true number is higher. Mixed carton sizes make it harder still.

Free Apparel Search tool

The Carton & Container Load Calculator handles mixed carton sizes, compares floor loading with US or EUR pallets, checks weight limits and shows a drawing of the load.

7. Add shipping to your costs

Freight, insurance, duty and fees all belong in your cost per garment, and the payments fall due at different times.

Free Apparel Search tools

Add them up with the Landed Cost Calculator, plan dates with the Production Timeline Planner and see when cash is due with the Import Cash Flow Planner.

Common mistakes to avoid


Questions

What is CBM?

CBM stands for cubic meter. A carton's CBM is its length x width x height in meters. Freight is often priced per CBM or by weight.

How many cartons fit in a 40-foot container?

It depends on the carton size, weight and how they are loaded. The free Carton and Container Load Calculator estimates it for your cartons.

What is the difference between FCL and LCL?

FCL means you book a full container. LCL means your cargo shares a container with other shippers, which suits smaller shipments.

What is volumetric weight?

It is a weight calculated from a carton's size, used so that light but bulky cargo is charged for the space it takes. Carriers charge the greater of actual and volumetric weight.

Should I palletize my shipment?

It depends on your customer and forwarder. Pallets speed up handling and are often required by retailers, but floor loading usually fits more cartons into a container.

Keep going

For general information only. This guide describes common practice and is not legal, financial or compliance advice. Customs, duty and shipping rules differ by country and carrier, so confirm details with your freight forwarder and customs broker. Apparel Search does not endorse any company listed in its directory. See our Legal page.