How to estimate storage volume

Storage is sold by volume and people think in rooms, which is why the first quote is usually wrong. This is the arithmetic: what a box holds, what a cubic metre is, how furniture converts, and a worksheet you can fill in walking round the flat with your phone.

Updated September 2026

The units

Storage companies quote in three units and they do not convert cleanly. Self storage rooms are sold by floor area in square metres, which hides the height: a 2 m² locker stacked 2.4 m high holds nearly 5 m³, while the same 2 m² under a low shelf holds one. Movers and some valet operators quote in cubic metres of truck or shelf. We quote in boxes, because a box is a thing you can picture and count. Our box is 60 × 40 × 40 cm outer, which is 0.096 m³, so ten boxes are about one cubic metre of contents and, allowing for the gaps and the odd shapes, four boxes take up a cubic metre of shelf. 12 boxes is therefore about 3 m³ of shelf, 24 about 6, 48 about 12.

Method one: count by room

Walk each room with your phone and write two numbers: boxes of loose things, and pieces of furniture. Loose things are anything that fits in a box: clothes, books, kitchen, bathroom, papers, toys, cables, decorations. Furniture is everything else. The table gives the usual range for a flat where everything goes; halve it if only the surplus is going.

Method two: convert the furniture

Furniture is where most estimates go wrong, because a wardrobe looks like one thing and takes the space of six boxes if it cannot be dismantled. Use the conversion table from our sizing guide: two-seat sofa 4, three-seat 5, corner sofa 6 to 8, armchair 2, fridge 3, washing machine 2, double mattress 2, queen or king 3, dismantled bed frame 2, dismantled wardrobe 3 (fixed carcass 6), dining table and four chairs 4, desk 2, bicycle 2, boxed television 1, air conditioner indoor unit 1. Anything not on the list: measure length, width and height in metres, multiply, and divide by 0.1 to get boxes. A 1.6 m by 0.8 m by 0.75 m table is 0.96 m³, call it 10 boxes if it does not dismantle and 3 if the legs come off.

Method three: measure a pile

If everything is already in one place, in the spare room or against the wall, measure the pile: length times width times height in metres gives cubic metres, and ten boxes per cubic metre gives the count. A pile 2 m long, 1 m deep and 1.2 m high is 2.4 m³, about 24 boxes, which is a Medium. This method overstates soft piles (bedding compresses, boxes stack tighter than a heap) and understates piles with a wardrobe in them, so use it as a check on method one rather than instead of it.

The worksheet

1. List each room. For each, write the box count for loose things from the table above, adjusted for what is actually going.
2. List each piece of furniture and each appliance that is going. Write its box equivalent next to it.
3. Add the two columns. That is your box-equivalent total.
4. Compare with the plans: up to 12 is Small, up to 24 Medium, up to 48 Large. Above 48 is quoted.
5. If the total sits within two or three of a boundary, take the plan above it. Being one box over costs the next plan; being ten boxes under costs nothing but the difference in monthly fee.

Mistakes that push people into the wrong plan

• Counting the cupboard, not its contents. A full built-in wardrobe is 5 to 7 boxes of clothes, not "one wardrobe".
• Forgetting the balcony, the top of the wardrobe and under the bed. These are where the suitcases, the fan, the Christmas box and the spare duvet live, and they add 4 to 6 boxes to most flats.
• Heavy boxes. Books and crockery are packed half full so that they can be lifted safely, which means two boxes where the volume says one.
• Assuming furniture dismantles. Many Vietnamese wardrobes and beds are glued or stapled; if it did not arrive flat-packed, count it whole.
• Assuming everything is going. Decide the sell and donate pile first; it is usually a fifth of the total and often the difference between two plans.

What happens on the day

The estimate sets the plan when you book. On collection day the crew packs, photographs and counts, and if the real number lands in a different plan the plan changes to match, up or down. Nobody is held to a guess. The only cost of a bad estimate is time: a Large that turns out to be a Small has a bigger truck than it needs for the morning.

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