Storage Unit Calculator
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Enter a custom space's length, width and height to get its volume in cubic feet and cubic yards, useful for checking a specific unit's real capacity, or for sizing a moving truck or shed against the same figure. The table below covers the four sizes most self-storage facilities offer as standard.
Standard Storage Unit Sizes
All four assume the typical 8 ft ceiling height most facilities build to, the same room-volume logic behind the BTU calculator, just applied to storage capacity instead of a cooling load.
| Unit Size | Floor Area | Approx. Volume | Typically Fits |
|---|---|---|---|
| 5 × 5 ft | 25 sq ft | ≈200 ft³ | A large closet: seasonal items, a few boxes |
| 5 × 10 ft | 50 sq ft | ≈400 ft³ | Studio contents or a single bedroom |
| 10 × 10 ft | 100 sq ft | ≈800 ft³ | Two bedrooms with appliances |
| 10 × 20 ft | 200 sq ft | ≈1,600 ft³ | A three or four bedroom house |
Sizing Against an Inventory, Not a Guess
The most reliable way to pick a unit is to build up from an actual inventory rather than eyeballing a room. Measure the largest individual pieces first, a sofa, a mattress, a wardrobe, a refrigerator, since these are the items most likely to make a "close" unit choice too tight in practice. Add the boxed total using the reference sizes below, then add roughly 10% on top for the air gaps that any real load contains, since furniture and boxes never stack with zero wasted space between them.
| Box Size | Capacity | Typical Contents |
|---|---|---|
| Extra small | ≈1 ft³ | Books, tools, tinned food |
| Small | ≈1.5 ft³ | Kitchenware, small electricals, files |
| Medium | ≈3 ft³ | Toys, pans, folded clothing |
| Large | ≈4.5 ft³ | Bedding, cushions, lampshades |
| Extra large | ≈6 ft³ | Duvets, pillows, coats, sports gear |
Why 70%, Not 100%, of the Nominal Figure
Every unit size in the table above assumes stacking solidly to the ceiling with zero wasted space, which almost never happens in practice, you need an aisle to reach items at the back, and fragile or oddly-shaped pieces can't stack as tightly as boxes can. Planning to fill about 70% of a unit's nominal cubic footage is a more realistic target than the full advertised number, and it's the same margin worth building into a moving-truck estimate if you're comparing storage against a shipping or freight volume figure for the same inventory.
If what you're actually trying to measure is a single object's interior capacity, a cabinet, a chest, a cooler, rather than a whole room's worth of belongings, the cubic inches calculator's fractional-inch support is often the faster tool for that narrower job.
Climate Control and Access Trade-Offs
This calculator's volume figures apply the same whether a unit is climate-controlled or not, the physical space doesn't change, but the decision between the two often affects what actually fits comfortably. Non-climate-controlled units are typically cheaper per cubic foot but expose contents to temperature and humidity swings that matter for wood furniture, electronics, photographs and anything else sensitive to moisture; climate-controlled units cost more but protect against that, which sometimes justifies stepping up to a larger unit than the bare volume calculation suggests, simply because a slightly bigger climate-controlled unit can be cheaper overall than a smaller one plus separately protecting sensitive items.
Drive-up units versus indoor units with a shared hallway present a similar trade-off that has nothing to do with volume: a drive-up unit lets you back a vehicle directly to the door, which matters enormously for heavy furniture and appliances, while an indoor unit usually costs less but requires carrying everything down a hallway. Neither choice changes the cubic-footage math on this page, but both affect how practical it is to actually move a given inventory into whichever unit size the calculation points to.
Vertical Space Most People Waste
The standard unit sizes in the table above assume filling to an 8 ft ceiling, but most people's actual packing only reaches shoulder height before they stop stacking, leaving several feet of unused vertical space at the top of every unit. Sturdy plastic bins and boxes with clearly labelled contents can usually be stacked three or four high safely, recovering a meaningful fraction of that wasted volume, the difference between packing to shoulder height and packing to within a foot of the ceiling can be enough to drop down an entire unit size, which is typically the single biggest cost lever available once you've already settled on what needs to go into storage.
Short-Term vs. Long-Term Storage Sizing
A short-term storage need, a few months during a move or renovation, often justifies packing tighter and accepting a smaller unit than a long-term arrangement would, since the inconvenience of a cramped unit is temporary. Long-term storage is worth sizing a bit more generously than the bare calculated minimum, both for easier access to individual items without unpacking half the unit, and because most people's stored inventory tends to grow rather than shrink over time. If your calculated figure lands right on the boundary between two standard unit sizes, lean toward the larger one for anything you expect to keep in storage for more than a few months.
It's also worth checking a facility's insurance or liability terms before assuming standard unit sizes are interchangeable across providers, the same nominal "10×10" designation can vary slightly between facilities depending on wall thickness and any support columns inside the unit, which can eat into the usable volume this calculator assumes is available.
Vehicles and Oversized Items
Vehicle, boat and RV storage is a separate category most facilities price and size differently from household unit storage, since the relevant dimension is often length and clearance height rather than cubic footage in the way this calculator computes it, a long, low vehicle can need a surprisingly large footprint even though its total volume stays modest. If you're storing a vehicle alongside household items rather than in a dedicated vehicle storage space, measure the vehicle's actual length, width and height (including mirrors and any roof-mounted equipment) directly rather than trusting a spec sheet's folded or collapsed dimensions, which are usually smaller than the vehicle's real parked footprint.
Frequently Asked Questions
Do standard storage unit sizes assume stacking to the ceiling?
Yes, and that assumption is rarely realistic, once you leave an access aisle and avoid stacking fragile items, planning to fill about 70% of a unit's nominal cubic footage is a safer basis for choosing a size than the full number.
How do I size a unit against my specific belongings instead of guessing?
Measure your largest items individually, a sofa, a mattress, a wardrobe, add the total from a box count using the reference table on this page, then add roughly 10% for the unavoidable air gaps in any real load. This approach catches oversized single items that a rough room-count guess tends to miss entirely.
Is a 10×10 unit big enough for a two-bedroom apartment?
Usually, if the apartment doesn't have unusually large furniture, 10×10 units are built around roughly 800 cubic feet at an 8 ft ceiling, which comfortably fits two bedrooms' worth of furniture and boxes for most households. A household with an oversized sofa or several major appliances should size up to the next unit instead.
Why do storage facilities advertise floor size rather than volume?
Floor dimensions are easier to visualize and compare at a glance than a cubic-foot figure, even though the volume up to the ceiling is what you're actually renting, this page's custom calculator lets you check the real volume behind the advertised floor size.