What size storage unit do I need?
What size storage unit you need depends less on how much you own than on how well you pack it and whether you need to walk inside. We read the size guides the big operators publish — Public Storage, Extra Space, CubeSmart, SpareFoot and several independents — and the chart below is where they agree, with the disagreements marked.
Unit sizes are quoted in feet, and the standard ceiling is 8 feet, so a 10x10 is around 800 cubic feet, not 100.
It's worth getting right the first time, because a unit is rarely the short rental people plan for. Industry figures for how long the average unit stays rented run from about 14 months at the low end to nearly 20 depending on who is counting, and a 10x10 averages somewhere around $120 a month nationally (StorageCafe, 2026). Whatever goes in there, you are paying by the month to keep it.
Storage unit size chart
| Size | Roughly | What the operators say it holds |
|---|---|---|
| 5x5 | A small closet | Boxes, seasonal clothes, a dresser, a small mattress set |
| 5x10 | A walk-in closet | About one bedroom's worth: a queen bed, a dresser, a TV, boxes |
| 10x10 | A small bedroom | A 1 bedroom apartment: a bedroom set, a couch, a small table, boxes |
| 10x15 | A large bedroom | A 2 bedroom home, and some sources say a small 3 bedroom |
| 10x20 | A one-car garage | A 2 to 3 bedroom house, and the first size most cars fit in |
| 10x30 | A two-car garage | A 4 to 5 bedroom house, or a car plus household goods |
Where the sources disagree: the 10x15 and 10x20 rows. Public Storage calls a 10x15 a 2-bedroom home; other guides put a 3-bedroom house in a 10x20 and say a 10x15 won't take it. Treat the boundary between those two as a judgment call, not a fact, and read the rule below before you pick.
Every one of these charts assumes a unit packed wall to wall and floor to ceiling, by someone who is good at it.
Two rules worth more than the chart
Size up one if you need to get at things. The moment you need to reach a box without unloading the unit, you need an aisle down the middle, and in a 10-foot-wide unit a two-foot walkway is a fifth of your floor gone before anything goes in. One of the 10x30 guides we read puts it more bluntly: without a retrieval aisle you lose the back third of a deep unit. Our own view is that this is the single most common sizing mistake, and that paying for the next size up beats the Saturday you'd spend unstacking.
Measure the four big things, not everything. You don't need to inventory a house to pick a size. Measure the sofa, the mattress set, the fridge and the largest dresser or table, and count your boxes. Those four pieces decide the footprint; boxes fill the gaps and go upward. Check the roll-up door opening too, since it is narrower than the unit.
Size down by packing upward
- Boxes of the same size stack square and go to the ceiling. Mixed box sizes waste a good deal of the height.
- Dressers and appliances hold things. Pack them full — linens, pillows, soft goods — rather than storing them empty.
- Mattresses, table tops, headboards and mirrors go upright against a side wall, taking inches instead of feet.
- Legs come off tables and chairs stack or nest seat to seat. One disassembled dining set is half a stored one.
How to not pay for a size you don't need
Rent month to month if you can, and ask what a smaller unit costs in the same building. Facilities usually let you move down a size, and a unit that's half empty after three months is money leaving every month for air.
The other direction is worth planning for too: storing more than you meant to is normal mid-move, and it's easier to downsize a unit once things settle than to find a second one in a hurry.
Whatever size you get, know what's in it
A storage unit you can't search is a storage unit you'll drive to and dig through. Number every box, note which unit it's in, and keep a list — how to make a storage unit inventory list walks through it, and the free storage label maker prints the labels.
We built Stow Haven to hold that list, with a photo of what went into each box and a search that forgives typos. It works offline and syncs when you're back in signal, which matters inside a metal building.
Questions
- What size storage unit do I need for a 2 bedroom apartment?
- Most operator size guides put a 2 bedroom home in a 10x15. A 10x10 can work for a lighter 2 bedroom or a full 1 bedroom, but it assumes the unit is packed wall to wall with no room to walk in.
- What size storage unit holds a 3 bedroom house?
- This is where published guides disagree. Some put a small 3 bedroom in a 10x15; others say plan on a 10x20, which is about a one-car garage and is also the first size most cars fit in. If the house is full or you want to reach things, take the 10x20.
- Should I get a bigger storage unit than I need?
- If you plan to visit the unit more than once, yes. Every size chart assumes a unit packed wall to wall and floor to ceiling, and in a 10-foot-wide unit a two-foot aisle is a fifth of the floor. Renting one size up is cheaper than a Saturday spent unstacking.
- How do I estimate what will fit in a storage unit?
- Measure the four biggest pieces — the sofa, the mattress set, the fridge and the largest dresser or table — and count your boxes. Those pieces decide the footprint; boxes fill the gaps and stack upward. Ask the facility how tall the ceiling is: 8 feet is standard, and a 10-foot ceiling is a quarter more volume for the same floor.