The most common — and most expensive — mistake people make with self storage is renting the wrong size unit. Rent too small and you're back the next week paying for a second unit. Rent too big and you're paying for empty air, month after month.
UK self storage units run from a 25 sq ft locker (about a garden shed) up to 200 sq ft and beyond (a double garage). This guide matches real-world belongings to the right unit size, room by room, so you book once and book right.
UK storage unit sizes at a glance
Here are the four standard sizes you'll find at most UK facilities, what each one realistically holds, and the typical monthly price:
| Unit size | Equivalent | What it holds | Typical price (per month) |
|---|---|---|---|
| 25 sq ft | Garden shed | ~30 boxes, suitcases, seasonal items | £40–£100 |
| 50 sq ft | Walk-in wardrobe | Contents of a one-bedroom flat | £95–£160 |
| 100 sq ft | Single garage | A two- to three-bedroom house | £190–£320 |
| 200 sq ft | Double garage / Luton van | A four- to five-bedroom house or business stock | £285–£450 |
Most facilities also stock in-between sizes (35, 75, 125, 150 sq ft) and smaller lockers (10–15 sq ft) for a handful of boxes. If your belongings fall between two sizes, the next section will help you decide which way to round.
How to work out what size you need
You don't need a tape measure and a spreadsheet. Use this three-step method:
- List the big items first. Sofas, beds, wardrobes, white goods, dining tables. These set your floor space — boxes fit around and on top of them.
- Count your boxes. A standard medium removal box is about 0.5 cubic feet of floor space when stacked. Thirty boxes stack comfortably into a 25 sq ft unit with room to spare.
- Add 10–15% for access. You'll want a narrow aisle to reach the back, especially for longer stays where you might retrieve items. Don't pack to the literal walls.
Stack high, not wide. Storage units typically have 8-foot ceilings. Strong boxes and sturdy furniture can be stacked to take advantage of the full height — vertical space is space you've already paid for.
Size guide by what you're storing
A few boxes or seasonal items — 25 sq ft
A 25 sq ft unit (5ft × 5ft) is the UK's most popular size for a reason. It swallows around 30 boxes plus a few bulky items — a bike, golf clubs, a chest of drawers, suitcases. It's the right choice for decluttering, seasonal storage (Christmas decorations, garden furniture over winter), and students stashing belongings over the summer holidays.
A one-bedroom flat — 50 sq ft
At 50 sq ft (5ft × 10ft, roughly a walk-in wardrobe), you can fit the contents of a one-bedroom flat: a sofa, double bed and mattress, wardrobe, chest of drawers, a few appliances, and 15–20 boxes. This is the workhorse size for people between tenancies, renovating a single room, or storing a partner's belongings while they travel.
A two- to three-bedroom house — 100 sq ft
A 100 sq ft unit (10ft × 10ft) is about the size of a single garage and holds a typical two- to three-bedroom house: multiple beds, sofas, a dining set, white goods, wardrobes, and 30+ boxes. It's the go-to for family house moves where there's a gap between completion dates, and for larger renovations.
A four- to five-bedroom house or business stock — 200 sq ft
At 200 sq ft (10ft × 20ft, a double garage or the load of a Luton van), you can store a four- to five-bedroom home or a serious volume of commercial stock. Growing e-commerce businesses use units this size as a low-cost alternative to warehousing, often with 24-hour access for order fulfilment.
Room-by-room quick reference
If you'd rather think in rooms than square feet:
| Your home | Recommended unit |
|---|---|
| Studio / single room of furniture | 25–35 sq ft |
| 1-bedroom flat | 50 sq ft |
| 2-bedroom home | 75–100 sq ft |
| 3-bedroom home | 100–125 sq ft |
| 4–5 bedroom home | 150–200 sq ft |
These are guides, not guarantees — a sparsely furnished three-bed needs less than a maximalist one-bed. When in doubt, see the next section.
Should you size up or size down?
When in doubt, size up. The cost gap between two adjacent sizes is usually £30–£60 a month. A second unit later costs far more — a whole extra base rent, plus the hassle of splitting your belongings across two spaces. A single slightly-larger unit is almost always cheaper and easier than two small ones.
The exception: for long-term storage where you're confident about the volume, sizing down and packing efficiently (stacking high, dismantling flat-pack furniture, filling drawers and appliances with smaller items) can save you hundreds over a year. If you're storing for 12+ months, it's worth packing a trial run in your garage or living room to gauge the true volume.
Most facility staff will happily walk you through the units in person before you commit — and many let you switch to a different size mid-contract if you've misjudged. Ask about that flexibility when you enquire.
Don't pay for space you don't need
Right-sizing is the single biggest lever on your storage bill. Before you book:
- Declutter first. Storage isn't a substitute for a decision. Sell, donate, or skip anything you won't want back — every item you don't store is space you don't pay for.
- Dismantle bulky furniture. Bed frames, tables, and flat-pack units take far less room disassembled. Keep screws in labelled bags taped to the piece.
- Use uniform boxes. Same-size boxes stack square and tall; odd shapes waste space and topple.
- Compare facilities on price-per-sq-ft, not just headline rate. Our Price Guide shows typical ranges, and each city page lets you compare nearby facilities side by side.
Once you know your size, search your postcode or city to compare real facilities near you — filter by the features you need and sort by price or rating.
Frequently asked questions
Still unsure? The answers below cover the questions we hear most. For a full price breakdown by size, see our UK Self Storage Price Guide.