How to count what you are storing
Walk through each room and count the large pieces, then count the boxes by size. For anything we do not list, measure its length, width and height in feet, multiply them, and add the result under anything else. A rough count is good enough, since the sizes come in big steps.
The volumes here were made to estimate truck loading, so they stand in for storage rather than measure it. Washington's regulator gives 60 cubic feet for a 4 cushion sofa, and 70 for a king bed. A mover's blog gives 4.5 for a large carton, 3 for a medium and 1.5 for a small one. Beds vary the most, as that blog gives 80 for a queen set and 100 for a king set, so add the difference if yours is a full set.
Then be honest about the height. CubeSmart says most units are 8 feet tall, but you only get that space if you can load to the ceiling. Heavy boxes and a sofa on end do not stack the same way, so this calculator starts at 6 feet, which is our own starting point.
A worked example
Here is a sofa, a bed, a dresser and a dining table, with 10 large boxes and 15 medium boxes, stacked to 6 feet. These lines come from the same formula the calculator above runs.
Furniture and 25 boxes, stacked to 6 ft
- 60 + 70 + 30 + 30 = 190 cu ft of furniture
- 10 × 4.5 = 45 cu ft of large boxes
- 15 × 3 = 45 cu ft of medium boxes
- 190 + 45 + 45 = 280 cu ft
- 280 × 1.15 = 322 cu ft with the allowance
- 15 × 5 × 6 = 450 cu ft usable
A 5 by 10 foot unit holds 300 cubic feet at this stack, which is a little short, so the answer goes up one step to a 5 by 15. If the 5 by 15 is not offered near you, the next size up is a 10 by 10. Use the moving cost calculator if you are moving these things as well as storing them.
Common storage unit sizes
The room guides disagree. CubeSmart gives a 10 by 10 for a 1 bedroom apartment and Public Storage gives it for 2 bedrooms, which is why counting beats going by rooms.
| Unit | Floor | To the ceiling | Stacked to 6 ft | Public Storage's room guide |
|---|---|---|---|---|
| 5 × 5 ft | 25 sq ft | 200 cu ft | 150 cu ft | Up to 10 large boxes |
| 10 × 5 ft | 50 sq ft | 400 cu ft | 300 cu ft | Studio |
| 15 × 5 ft | 75 sq ft | 600 cu ft | 450 cu ft | 1 bedroom |
| 10 × 10 ft | 100 sq ft | 800 cu ft | 600 cu ft | 2 bedrooms |
| 15 × 10 ft | 150 sq ft | 1200 cu ft | 900 cu ft | 2 bedroom home |
| 20 × 10 ft | 200 sq ft | 1600 cu ft | 1200 cu ft | 3 bedroom home |
| 25 × 10 ft | 250 sq ft | 2000 cu ft | 1500 cu ft | 4 bedroom home |
| 30 × 10 ft | 300 sq ft | 2400 cu ft | 1800 cu ft | Not listed in this guide |
Mistakes when choosing a unit
- Counting every cubic foot. Odd shapes, aisles and fragile things that cannot carry a stack all take away from the gross figure.
- Leaving no path. If you will need things during the rental, leave a way to reach them, and expect to want a larger unit.
- Going by rooms alone. A 10 by 10 is a 1 bedroom at one chain and 2 bedrooms at another. Count your things.
- Assuming the height. Most units are 8 feet, but CubeSmart says it may depend on the facility, so ask the store manager.
- Assuming climate control. Public Storage says it does not guarantee temperature or humidity ranges.
Questions
What fits in a 10x10 storage unit?
About 40 boxes, on Public Storage's figures, or the contents of a 1 or 2 bedroom home. CubeSmart calls it a 1 bedroom apartment size, and Public Storage says 2 bedrooms. Its floor is 100 square feet, with 800 cubic feet to an 8 foot ceiling.
What size unit for a 2 bedroom apartment?
A 10 by 15 foot unit is the safer choice, and a 10 by 10 may do. CubeSmart gives 10 by 15, or possibly 10 by 10. Public Storage lists a 10 by 10 for 2 bedrooms and a 10 by 15 for a 2 bedroom home.
What size storage unit for a 1 bedroom apartment?
A 5 by 15 to a 10 by 10 foot unit. Public Storage says 5 by 15, and CubeSmart says 10 by 10. Counting what you own here will show which end you are at.
What size storage unit for a 3 bedroom house?
A 10 by 20 foot unit, and up to a 10 by 30. Public Storage lists a 10 by 20, and CubeSmart gives 10 by 20 or 10 by 30. A mover's blog puts a 3 bedroom home at 1,200 to 1,800 cubic feet.
How tall are storage units?
Most are 8 feet tall, by CubeSmart, though it says this can depend on the facility. Its lockers are 4 feet tall. Ask the manager for the height of the unit you are renting before you plan to stack high.
What can I not keep in a storage unit?
Unsafe, hazardous, illegal or perishable goods, and anything living, by Public Storage. It also says it does not guarantee temperature or humidity ranges, so ask before you store anything that could be damaged by either one.
This unit size is an estimate. The item volumes come from haulage tables for loading trucks, so they only approximate what a unit holds, and awkward shapes or fragile pieces take more room. Sizes vary between chains, so look inside the unit first, and ask the supplier about its height and what may be kept there.
Sources and review
- Size guide, CubeSmart, no date shown, read November 2026.
- Size guide, Public Storage, no date shown, read November 2026.
- Completed cube sheet, Washington Utilities and Transportation Commission, no date shown, read November 2026.
- How to estimate cubic feet for a long-distance move, Safebound Moving & Storage, 2026.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Space needed
Needed = Sum of items × (1 + Allowance ÷ 100)
- Allowance
- Percent added for gaps, our own assumption
Worked through: 280 × 1.15 = 322 cu ft
Usable space
Usable = Floor area × Stack height
- Stack height
- How high you can load, in feet
Worked through: 75 × 6 = 450 cu ft
The constants, and where they come from
REGULATED_ITEM_CU_FT
Published figureCubic feet for a sofa, a king bed, a small desk and a night table
- sofa
- 60
- bed
- 70
- desk
- 22
- nightTable
- 5
Applies to: A mover's estimate of truck space, used here as a stand-in for storage
Source: Completed cube sheet, Washington Utilities and Transportation Commission, no date on the page, read 2026-11.
Rows from the Washington regulator's table: sofa with 4 cushions 60, king bed 70, small desk 22, night table 5. These measure what a truck carries, not what a unit holds.
MOVER_ITEM_CU_FT
Modelled from published dataCubic feet for a dresser, a table, a refrigerator and cartons
- dresser
- 30
- diningTable
- 30
- refrigerator
- 50
- wardrobeBox
- 13
- largeBox
- 4.5
- mediumBox
- 3
- smallBox
- 1.5
Applies to: One mover's figures, used as a stand-in for storage
Source: How to estimate cubic feet for a long-distance move, Safebound Moving & Storage, published 2026-06, read 2026-11.
We could not read a full public table. Safebound's own FAQ gives a dresser 15 to 20 cubic feet against 30 in its table, and it gives 80 for a queen set and 100 for a king set.
STANDARD_UNITS
Published range, narrowedCommon unit sizes in feet, smallest first
- 0
- 5, 5
- 1
- 10, 5
- 2
- 15, 5
- 3
- 10, 10
- 4
- 15, 10
- 5
- 20, 10
- 6
- 25, 10
- 7
- 30, 10
Applies to: United States chains. Availability varies by facility
Source: Size guide, CubeSmart, no date on the page, read 2026-11.
Also from: Size guide, Public Storage, no date on the page, read 2026-11.
CubeSmart lists 5 by 5 up to 10 by 30. Public Storage adds 5 by 15 and 10 by 25. Public Storage says sizes are approximate and may vary.
UNIT_HEIGHT_FEET
Published range, narrowedHeight of most units, in feet
Applies to: Most units. CubeSmart says it may depend on the facility
Source: Size guide, CubeSmart, no date on the page, read 2026-11.
CubeSmart's volumes equal the floor area times 8 feet. Its lockers are 4 feet tall, and they are not offered here.
DEFAULT_PACKING_ALLOWANCE_PERCENT
Modelled from published dataExtra space added for gaps between items, in percent
Applies to: Our own assumption, which you can change
Source: How to estimate cubic feet for a long-distance move, Safebound Moving & Storage, published 2026-06, read 2026-11.
No source gives a packing allowance. Safebound says loading skill shifts truck use by 10 to 15 percent, which is about trucks. We took the upper figure as a default.
What the labels mean
- Published figure:
- taken directly from the source named beside it.
- Modelled from published data:
- derived rather than measured, calibrated against the source named beside it.
- Published range, narrowed:
- a source publishes a range and this calculator uses a representative value from it.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the storage unit size calculator
- 1
Count your furniture
- 2
Count your boxes by size
- 3
Add anything else in cubic feet
- 4
Say how high you can stack
- 5
Book the size it shows, and look inside before you sign
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- Item volumes come from mover tables, as a stand-in for storage
- A 15 percent packing allowance is our own assumption, and you can change it
- A stack height of 6 feet is our own starting point
- Units are the common sizes, and availability varies
Pro tips
- Look inside the unit before you sign
- Put what you will need near the door
- Ask the manager for the height of your unit