20ft vs 40ft Container Capacity: Which is Best for Amazon FBA?

For Amazon FBA sellers scaling up from small air shipments to sea freight, the first major decision is choosing the right container size. The two industry standards are the 20ft General Purpose (GP) and the 40ft General Purpose (GP) container.

Choosing the wrong one creates “dead space”—air you are paying to ship across the ocean. In this guide, we break down the capacity differences and help you decide which one fits your FBA strategy.

20ft Standard Container (TEU)

The 20ft container is the most common starter container for small-to-medium businesses. In the industry, it is often called a TEU (Twenty-foot Equivalent Unit).

• Internal Length: 5.90 m (19.4 ft)
• Internal Width: 2.35 m (7.7 ft)
• Internal Height: 2.39 m (7.9 ft)

How Much Fits Inside?

• Theoretical Maximum: 33 CBM
• Realistic Usable Space: 25 to 28 CBM

Why the difference? You cannot stack boxes perfectly to the roof without gaps. Pallets, cardboard thickness, and door clearance reduce usable space.

Best For: Heavy goods. Since shipping lines charge by container, not weight (up to a limit), 20ft containers are ideal for dense items like metal parts, machinery, or liquids where you hit the weight limit before filling the volume.

40ft Standard Container (FEU)

The 40ft container offers double the volume but, surprisingly, usually doesn’t cost double the price of a 20ft. It is often only 30-40% more expensive, making it much more cost-effective for volume.

• Internal Length: 12.03 m (39.5 ft)
• Internal Width: 2.35 m (7.7 ft)
• Internal Height: 2.39 m (7.9 ft)

How Much Fits Inside?

• Theoretical Maximum: 67 CBM
• Realistic Usable Space: 54 to 58 CBM

Best For: Bulky, light items. Furniture, toys, textiles, and most Amazon FBA consumer goods.

The 40ft High Cube (HQ): The FBA Favorite

There is a third option that most experienced Amazon sellers prefer: The 40ft High Cube. It is exactly the same length and width as a standard 40ft, but it is 30cm (1 foot) taller.

• Extra Capacity: Gives you roughly 63 to 68 CBM of usable space.
• Price Difference: Often the same price or very slightly higher than a standard 40ft.

Pallet Loading for Amazon FBA

Amazon usually requires shipments to be palletized if they are going to certain Fulfillment Centers. This drastically reduces how much you can fit.

Standard 20ft Container Capacity:

• Floor Loaded (Loose boxes): ~28 CBM
• Palletized (Standard Pallets): ~10 Pallets (1 row, no stacking) or ~20 Pallets (stacked, difficult).

If you palletize, you lose about 15-20% of your container’s volume to the pallets themselves and the inability to stack to the roof.

Summary: Which Should You Choose?

1. Use a 20ft Container if: You have between 15 CBM and 28 CBM of goods.
2. Use a 40ft Container if: You have more than 30 CBM. It is cheaper than two 20ft containers.
3. Use a 40ft HQ if: You are shipping light, bulky items and need every inch of height.