How Many Boxes Fit in a 20ft or 40ft Container? (With the Math)

Quick answer: There’s no single number — it depends on your carton size. As a rule of thumb, a common 40 × 30 × 30 cm box fits roughly 780 in a 20ft and 1,600 in a 40ft container once you allow for real-world packing. The way to get your number is simple: divide the container’s usable volume by the volume of one box, then knock off ~15% for the space you can never fill.

That’s the generic box — yours is different. A 40 × 30 × 30 cm carton is just an example. Enter your real box dimensions, weight and quantity to get the exact count plus how full each container runs — instantly, free, no signup.

Run my boxes through the free calculator →

The formula

Boxes ≈ (container volume ÷ box volume) × fill factor

• Container volume: ~33.2 m³ for a 20ft, ~67.7 m³ for a 40ft (full dimensions here).
• Box volume: length × width × height of one carton, in metres. A 40 × 30 × 30 cm box is 0.40 × 0.30 × 0.30 = 0.036 m³.
• Fill factor: ~0.85 for uniform boxes that stack neatly; lower for odd sizes or mixed loads. You never reach 100% — there are always gaps, and the door and walls steal space.

So for that box in a 40ft: 67.7 ÷ 0.036 = 1,880 theoretical, × 0.85 ≈ 1,600 boxes.

How many boxes fit, by carton size

Approximate counts at a realistic ~85% fill. Find the row closest to your carton:

Carton size (L × W × H)	Box volume	20ft (~33 m³)	40ft (~68 m³)
30 × 30 × 30 cm	0.027 m³	~1,045	~2,130
40 × 30 × 30 cm	0.036 m³	~780	~1,600
60 × 40 × 40 cm	0.096 m³	~295	~600
50 × 50 × 50 cm	0.125 m³	~225	~460

A 40ft holds almost exactly double a 20ft, because it has the same width and height and twice the length.

The catch: weight, not just space

Volume is only half the picture. Every container caps at a 30,480 kg gross weight — a payload of roughly 28,000 kg in a 20ft and 26,500 kg in a 40ft. Do the second sum:

1,600 boxes at 20 kg each = 32,000 kg — over the limit. You’d actually load ~1,300 boxes before the floor gives out on weight, even though the volume says 1,600.

This is the mistake that gets shipments turned away at the port. Dense goods (bottled liquids, ceramics, hardware) are weight-limited; light, bulky goods (textiles, packaging) are volume-limited. Always check both. If you only need the volume side first, the free CBM calculator converts a carton list to cubic metres in seconds.

Why orientation changes the answer

The formula assumes boxes pack perfectly, but a 40 cm box doesn’t divide evenly into a 2.35 m width (2.35 ÷ 0.40 = 5.875 → only 5 fit across, wasting 35 cm). Rotating cartons, mixing two box sizes, or choosing a carton that tiles the width cleanly can swing the real count by 10–20%. That’s exactly the optimisation a load planner does for you.

Get the exact count for your boxes

Rules of thumb get you a ballpark; a plan gets you the real number. ContainerMath is container loading software that takes your actual carton dimensions, weights and quantities and computes a 3D load plan — how many fit, in what orientation, and how much volume and payload you’re using — across 20ft, 40ft, High Cube and truck vessels.

See it packed in 3D — free trial →

Frequently asked questions

How many boxes fit in a 20ft container?

For a standard 40 × 30 × 30 cm carton, roughly 780 boxes at a realistic packing density. The exact number is your container’s ~33 m³ ÷ your box volume × ~0.85 — and capped by the ~28,000 kg weight limit.

How many boxes fit in a 40ft container?

About double a 20ft — roughly 1,600 of those 40 × 30 × 30 cm cartons — unless the cargo is heavy, in which case the ~26,500 kg payload limit binds first.

Why can’t I fill 100% of the container?

Box dimensions rarely divide evenly into the container’s interior, so there are always gaps; the door opening and wall thickness also reduce usable space. A 75–90% fill is normal for uniform boxes, lower for mixed loads.

Should I count by boxes or by pallets?

If your boxes ship on pallets, plan by pallet instead — see how many pallets fit in a 20ft or 40ft container. Loose-loaded (floor-stacked) boxes fit more units but take far longer to load and unload.