Choosing a refrigerated container begins with two numbers that never quite agree: what the unit measures on the outside, and what you can actually load inside. On a reefer that gap is wider than on a plain dry box, because the insulation that keeps the cold in also eats into every internal dimension, and the refrigeration unit claims a slice of the length. This guide sets out external and internal dimensions, volume, pallet capacity and tare for the three common formats — 10ft, 20ft and 40ft high cube — using standard ISO measurements, then explains why the inside is smaller and how much ground and access a delivery genuinely needs.
External and internal dimensions
External dimensions are fixed by ISO standard, so a 20ft reefer is the same 6.06 m long as a 20ft dry box and stacks and ships the same way. Internal dimensions are not standardised in that manner — they depend on how thick the insulation is — but the figures below are representative of units on the UK market.
| Format | External L × W × H | Internal L × W × H | Tare |
|---|---|---|---|
| 10ft | ≈ 2.99 × 2.44 × 2.59 m | usable length well below the external figure | — |
| 20ft | 6.06 × 2.44 × 2.59 m | ≈ 5.44 × 2.29 × 2.27 m | ≈ 3,000 kg |
| 40ft high cube | 12.19 × 2.44 × 2.90 m | ≈ 11.58 × 2.29 × 2.55 m | ≈ 4.5 tonnes |
Two figures deserve a flag. The 10ft is roughly 2.99 m long overall — treat that as an external footprint, never as usable internal length, because on such a short box the insulation and the refrigeration unit take a proportionally large bite out of the floor. And on the 40ft high cube the internal height is 2.55 m: the extra height over a standard 40ft is the entire point of the “high cube” badge, and it is that internal figure, not the 2.90 m external, that decides whether a tall load fits.
Why the interior is smaller
A refrigerated container is a dry container turned into an insulated box, and that costs space on every face:
- Every surface loses thickness. A 20ft reefer is 2.44 m wide and 2.59 m tall outside, but about 2.29 m wide and 2.27 m tall inside — roughly 150 mm off the width and 320 mm off the height, all of it foam panel in the walls, roof and floor.
- The machinery end shortens the box. The 6.06 m external length becomes about 5.44 m of usable floor, because the refrigeration unit is built into one end and occupies the difference.
The result is that a reefer holds noticeably less than a dry container of the same nominal size. Always plan a load around the internal dimensions, and remember that internal height — 2.27 m on a 20ft, 2.55 m on a 40ft high cube — is what limits tall or double-stacked pallets.
Volume, pallets and payload
Turn those internal dimensions into the capacity figures that matter for planning:
| Format | Usable volume | Pallets (floor) | Payload |
|---|---|---|---|
| 10ft | ≈ 15 m³ | 4 – 5 | — |
| 20ft | ≈ 28 m³ | 10 – 11 | ≈ 27 tonnes |
| 40ft high cube | ≈ 67 m³ | 23 | — |
Pallet counts are floor positions for standard pallets; where headroom lets you double-stack safely, effective capacity rises with the internal height, which is precisely why the high cube earns its name. The 20ft carries a substantial payload — around 27 tonnes on a tare of roughly 3,000 kg — but weight limits are set by the unit’s rating and by road regulations, so confirm both before loading to the maximum. If you are weighing up which size to own, our prices page sets out what each format costs, while the hire and for-sale sections show what is on the market new and used.
Footprint and lorry access
A container needs more room than its own footprint. On the ground a 20ft occupies about 6.06 × 2.44 m, a 40ft high cube about 12.19 × 2.44 m and a 10ft around 2.99 × 2.44 m — but that is only the box. Delivery is normally by a crane-equipped lorry that has to draw up alongside the final position and lift the unit into place, so allow for:
- Firm, level ground that will carry the loaded weight without sinking.
- Clear access for a long rigid lorry to reach the spot and stand beside it.
- Overhead clearance — no cables, branches or eaves in the lift path.
- Swing room to one side for the crane arm to work.
A high cube also stands 2.90 m tall, so check door heights and gateway clearances along the whole approach, not just at the final spot. And because a reefer needs power to earn its keep, position it within reach of a suitable three-phase supply; our other guides cover the electrical side in detail.
Matching the size to your load
Size selection comes down to matching internal volume and pallet count to the load, not the external badge on the door. Under-size the unit and product stays outside; over-size it and you pay to cool empty space for the length of the hire or the ownership. Work from the internal dimensions, sketch how your pallets sit on the floor, and leave headroom for air to circulate around the load.
Once you know the format you need, describe your requirement once and we pass it to specialist suppliers, who contact you directly if they can meet your need.
Frequently asked questions
What are the internal dimensions of a 20ft refrigerated container?
Inside, a 20ft reefer measures roughly 5.44 m long, 2.29 m wide and 2.27 m high, against external dimensions of 6.06 × 2.44 × 2.59 m. Insulation on every surface and the refrigeration unit at one end account for the gap. That usable space holds about 28 m³ and 10 to 11 standard pallets, on a tare of around 3,000 kg.
Why is a refrigerated container smaller inside than a dry container?
Because a reefer is insulated on all six surfaces. Thick foam panels in the walls, roof and floor take thickness off every internal measurement, and the refrigeration unit occupies a slice of the length at one end. A 40ft high cube stands 2.90 m tall outside but only 2.55 m inside, so always plan a load around the internal figures rather than the external ones.
How many pallets fit in a 40ft high cube reefer?
About 23 standard pallets sit on the floor of a 40ft high cube, which offers roughly 67 m³ of insulated space and a 2.55 m internal height. A 20ft takes 10 to 11 pallets and around 28 m³; a 10ft holds 4 to 5 pallets and about 15 m³. Where headroom allows safe double-stacking, effective capacity climbs with that internal height.
How much ground space and access does a refrigerated container need?
The footprint is only the box: about 6.06 × 2.44 m for a 20ft, 12.19 × 2.44 m for a 40ft high cube and roughly 2.99 × 2.44 m for a 10ft. Delivery is usually by a crane-equipped lorry that must draw up alongside and lift the unit into place, so allow firm, level ground, clear overhead clearance and swing room for the crane arm.