What size storage unit do you need?
Renting the wrong storage unit is an expensive mistake in both directions. Too small, and you end up stacking boxes to the ceiling, blocking access to everything at the back, or renting a second unit at short notice. Too large, and you pay for empty floor space every month for a year. The right size follows fairly predictably from the size of the home being stored, because furniture and boxes scale with rooms, and the calculator on this page maps bedrooms to the standard unit sizes that storage facilities actually sell, with dimensions and cubic footage so you can compare like with like.
Storage units are sold by floor area, but what you are really buying is volume, because most units are about eight feet high and stacking is how the space gets used. A five-by-five unit is twenty-five square feet and about two hundred cubic feet, roughly a large closet. A five-by-ten is fifty square feet, about four hundred cubic feet, and holds a small one-bedroom flat. A ten-by-ten is one hundred square feet and eight hundred cubic feet, the classic two-bedroom size. Ten-by-fifteen and ten-by-twenty cover three and four bedrooms, and ten-by-thirty, the size of a single garage and more, handles a large house or a house plus a vehicle. Knowing the cubic feet helps you judge whether your belongings will genuinely fit once stacked, rather than just spread on the floor.
The standard sizes, room by room
A studio or a single room of furniture fits a five-by-five: a twin mattress set, a few boxes, a bicycle, and small items. A one-bedroom flat needs a five-by-ten, which takes a queen mattress set, a sofa or loveseat, a small dining set, and twenty to thirty boxes. Two bedrooms move up to a ten-by-ten, with room for two mattress sets, a sofa, appliances, and forty or more boxes. Three bedrooms need a ten-by-fifteen, and four bedrooms a ten-by-twenty, which is roughly a one-car garage and handles a full house including major appliances. Five or more bedrooms, or a house plus a car, call for a ten-by-thirty. These are starting points: a sparsely furnished home can drop a size, while a home with a garage, a workshop, or heavy furniture may need to go up one.
| Home size | Unit size | Floor area | Volume (8 ft high) |
|---|---|---|---|
| Studio | 5 x 5 ft | 25 sq ft | 200 cu ft |
| 1 bedroom | 5 x 10 ft | 50 sq ft | 400 cu ft |
| 2 bedrooms | 10 x 10 ft | 100 sq ft | 800 cu ft |
| 3 bedrooms | 10 x 15 ft | 150 sq ft | 1,200 cu ft |
| 4 bedrooms | 10 x 20 ft | 200 sq ft | 1,600 cu ft |
| 5+ bedrooms | 10 x 30 ft | 300 sq ft | 2,400 cu ft |
Measuring before you rent
Before you sign, measure your largest items: sofa length, mattress size, wardrobe height, and any appliance. A ten-by-ten unit sounds generous until a three-seater sofa and a king mattress occupy most of one wall. Sketch a rough floor plan on paper and place the big items first, leaving a walkway down the middle so you can reach the back without unloading half the unit. Stack boxes by weight, heavy at the bottom, and fill furniture cavities: drawers, wardrobes, and washing machines all hold soft items. Disassemble beds and tables where possible, because flat-packed furniture uses far less volume than assembled furniture and stacks more safely.
Also count your boxes honestly. A typical bedroom produces fifteen to twenty boxes, so a two-bedroom home means thirty to forty boxes before furniture, and boxes stack four or five high only if they are uniform and well packed. If you have already packed, count the boxes and multiply by about one and a half cubic feet per medium box to estimate their total volume. That single check catches most under-sizing mistakes, because people consistently underestimate box volume and overestimate how neatly boxes stack in a real unit with awkward furniture shapes in the way.
Climate control and what should not be stored
Standard drive-up units are fine for most household goods, but climate-controlled units, which keep temperature and humidity in a moderate range, are worth the premium for wood furniture, leather, electronics, photographs, documents, musical instruments, and anything that warps, cracks, or grows mould. If your region has hot summers, freezing winters, or high humidity, climate control protects the items most likely to be damaged, and it is usually cheaper than replacing them. Never store food, plants, animals, flammable liquids, paint, propane tanks, or anything perishable or hazardous; facilities prohibit these, and they attract pests or create fire risk for everyone in the building.
Security and access deserve the same attention as size. Look for gated access, lighting, cameras, and individual unit alarms, and use a disc lock rather than a standard padlock, because disc locks are much harder to cut. Check access hours against your real needs: if you will visit on weekends or evenings, a facility with restricted hours will frustrate you quickly. Ask about insurance, because facility coverage is usually limited, and your home insurance may or may not extend to stored goods. Photograph the unit as you load it, keep an inventory list, and put items you will need first near the door.
Business and vehicle storage
Small businesses use storage for stock, tools, and archives, and the same sizing logic applies: measure shelving and pallet footprints, not just box counts, and leave aisle space for picking. A ten-by-ten with shelving along the walls holds a surprising amount of stock, while a ten-by-twenty suits a tradesperson with tools, ladders, and materials. Vehicles need dedicated sizing: a motorcycle fits in a five-by-ten, a standard car needs a ten-by-twenty, and boats and caravans need outdoor or extra-large covered spaces measured by length. Always check door width and height for vehicles, because a unit that is long enough but has a narrow door is useless.
Costs and common mistakes
Monthly rent rises steeply with size, so dropping one size by packing efficiently can save hundreds over a year, but upgrading mid-contract is usually easy, while downgrading means moving everything twice. Ask about introductory offers carefully: a low first-month rate that jumps later can cost more than a stable rate elsewhere, and check the notice period for vacating. The most common mistakes are renting by guesswork instead of measuring, stacking boxes directly on concrete floors where moisture wicks in, and burying needed items behind furniture. Pallets or plastic sheeting under boxes, a walkway down the middle, and a labelled map on the door solve all three.
- Measure your largest furniture before choosing a unit.
- Leave a walkway so the back of the unit stays reachable.
- Count boxes: about 1.5 cu ft per medium box.
- Use climate control for wood, leather, electronics, and photos.
- Use a disc lock, and photograph your inventory.
The right unit is the smallest one your belongings genuinely fit in, with a walkway and a little breathing room. Use the calculator above to find your size, measure your biggest items to confirm it, and rent with confidence instead of guesswork.
Short-term versus long-term storage
How long you plan to store changes the calculation. For a short stay of a month or two during a move, a slightly larger unit is forgiving, because you will not be living with the monthly cost for long, and easy access matters more than perfect efficiency. For long-term storage of a year or more, the monthly rent dominates, so packing tightly and choosing the smallest workable unit saves real money, and climate control becomes more important, because a full year of seasons will test anything sensitive. Review a long-term unit every six months: sell, donate, or reclaim items you no longer need, because paying to store things you have forgotten you own is the most common storage regret. A unit that shrinks over time as you declutter is a sign the system is working.