Quick answer: cubic feet = length × width × height (inches) ÷ 1,728. A standard medium box at 18 × 18 × 16 in is exactly 3 ft³. For a whole move, budget 150–200 ft³ per furnished room.
Standard moving box sizes
| Box | Dimensions | Volume | Pack it with |
|---|---|---|---|
| Small (book box) | 16 × 12 × 12 in | 1.33 ft³ | Books, tools, tinned food |
| Medium | 18 × 18 × 16 in | 3.0 ft³ | Kitchenware, toys, small appliances |
| Large | 18 × 18 × 24 in | 4.5 ft³ | Bedding, towels, lampshades |
| Extra large | 24 × 18 × 24 in | 6.0 ft³ | Duvets, pillows, soft bulky items |
| Wardrobe | 24 × 21 × 48 in | 14.0 ft³ | Hanging clothes |
| Dish barrel | 18 × 18 × 28 in | 5.25 ft³ | Crockery and glassware |
| Picture / mirror | 37 × 4 × 27 in | 2.31 ft³ | Framed art, mirrors |
The golden rule of packing runs against instinct: heavy things go in small boxes. A large box filled with books can exceed 100 lb, which is unliftable and will burst at the seams. Books in book boxes, pillows in extra-larges.
Sizing a whole move
| Home | Volume | Boxes | Truck |
|---|---|---|---|
| Studio | 200–300 ft³ | 20–35 | 10 ft |
| 1 bedroom | 300–400 ft³ | 30–50 | 10–15 ft |
| 2 bedroom | 600–800 ft³ | 60–90 | 15–20 ft |
| 3 bedroom | 1,200–1,600 ft³ | 100–150 | 20–26 ft |
| 4+ bedroom | 1,800–2,400 ft³ | 150–220 | 26 ft + |
Two corrections worth applying to any estimate. First, packing efficiency runs 80–85%, not 100 — furniture is awkward, boxes don't tessellate, and you need room to work. Second, almost everyone underestimates; if you are between two truck sizes, take the larger one. A second trip costs far more than the size difference.
Storage unit sizes
| Unit | Floor area | Volume (8 ft ceiling) | Roughly holds |
|---|---|---|---|
| 5 × 5 ft | 25 ft² | 200 ft³ | A small closet's contents |
| 5 × 10 ft | 50 ft² | 400 ft³ | Studio / 1-bed flat |
| 10 × 10 ft | 100 ft² | 800 ft³ | 2-bedroom home |
| 10 × 15 ft | 150 ft² | 1,200 ft³ | 3-bedroom home |
| 10 × 20 ft | 200 ft² | 1,600 ft³ | 4-bedroom home |
Storage is advertised by floor area, but you pay for the volume — so stacking height matters. A 10 × 10 unit with an 8-foot ceiling holds twice what you would guess from the floor plan if you stack properly and leave an access aisle.
Common mistakes & pro tips
- Dividing by 12 instead of 1,728. All three dimensions convert, so the divisor is 12³.
- Assuming perfect packing. Apply the 80–85% rule to any truck or unit sizing.
- Large boxes for heavy goods. Weight, not volume, is what makes a box fail.
- Inside versus outside dimensions. Inside for what fits; outside for what a carrier bills. The gap matters most in thick-walled boxes — the same reason a rectangular tank's true capacity falls short of its outside measurements.
- Net versus gross internal volume. Anything mounted inside a box steals from its usable space. Speaker builders subtract driver and port displacement for exactly this reason — see the subwoofer box volume calculator.
- Pro tip — check dimensional weight before shipping. A light, bulky box is billed on its size. The volumetric weight calculator shows what you will actually pay.
- Pro tip — measure furniture separately. Sofas and mattresses dominate a move's volume and never fit a box. Add them as individual items to your total.
Frequently asked questions
How do I calculate the volume of a box?
Multiply length × width × height. In inches, divide the result by 1,728 for cubic feet. A standard medium moving box at 18 × 18 × 16 inches is 5,184 in³, which is exactly 3 cubic feet.
How many boxes do I need to move?
A common planning figure is 30 to 40 boxes per fully furnished room, split across small, medium and large sizes. A one-bedroom apartment usually needs 30 to 50 boxes in total, a three-bedroom house 100 to 150. Books and heavy items should always go in small boxes regardless of what space remains.
How much space do I need in a moving truck?
Plan on 150 to 200 cubic feet per furnished room. A one-bedroom apartment typically needs 300 to 400 cubic feet, which suits a 10-foot truck; a three-bedroom house at 1,200 to 1,600 cubic feet needs a 20 to 26 foot truck.
Should I measure the inside or outside of a box?
Inside, if you want to know what fits. Corrugated cardboard takes roughly a quarter inch off each internal dimension, which is minor for a large box but noticeable on small ones. Carriers, however, bill on outside dimensions, so use the outside when calculating shipping costs.
How full can I realistically pack a truck?
About 80 to 85 percent, not 100. Furniture is irregular, boxes do not tessellate perfectly and you need aisles to load. Always size the truck against your volume plus that inefficiency, and it is cheaper to book one size up than to make a second trip.