Storage unit size estimator
Compare the volume of what you plan to store with a list of storage unit sizes, allowing for stacking height, packing gaps and an access aisle. It picks the smallest unit that fits and shows how full each would be.
Up to 500 items (sides above 0 and up to 20 m, quantity 1 to 1,000) or a known volume up to 100,000 m³; packing efficiency 10 to 100%, clear floor share 0 to 90%, stacking height up to 10 m and up to 50 unit sizes. Calculated on your device; download a JSON report and CSV files of results and the unit comparison. This calculator uses the item list, unit sizes and other fields only. Up to 1,000,000 characters. Review the settings before running.
Your result
How to use Storage unit size estimator
- List your items with length, width, height and quantity, or switch to a known total volume.
- Set the packing efficiency, the floor share kept clear for access and the highest you will stack.
- Edit the storage unit sizes to match the provider you are considering.
- Review the smallest fitting unit and the comparison table, then download the CSV.
Useful next steps
Usable volume of a unit
Things never fill a unit perfectly, so usable volume is floor area, minus the share kept clear for access, times the lower of your stacking height and the ceiling, times packing efficiency. A 5 × 15 ft unit with 15% kept clear, stacked to 7 ft at 75% efficiency, holds 75 × 0.85 × 7 × 0.75 = 334.7 ft³.
Smallest unit that fits
The example list totals 291.25 ft³, so the 5 × 10 ft unit (223.1 ft³ usable) is too small and the 5 × 15 ft unit fits at 87% full. The floor area needed, about 65.3 ft², is the same calculation without a particular unit.
Unit sizes
The default sizes are common United States units from the Public Storage size guide (checked 16 October 2026), which lists 5 × 5 ft at 200 ft³ through 10 × 25 ft at 2,000 ft³, implying 8 ft ceilings. Providers differ, so replace them with the sizes you can rent.
Limits
Up to 500 items with sides up to 20 m and quantities up to 1,000, a known volume up to 100,000 m³, and up to 50 unit sizes. Door openings, shelving and awkward shapes are not checked; an item taller than your stacking height in every direction is flagged.