How the storage unit estimate works
The calculator first assigns a visible approximate packed volume to each item category. It multiplies those values by your counts and adds any custom volume. It then divides the inventory total by the selected packing efficiency: 80% for a dense stack without a permanent aisle, 70% for occasional access, or 55% for a clearer route used more regularly. Dividing by efficiency creates room for unavoidable gaps, awkward shapes and access rather than pretending every cubic foot can hold belongings.
The result is compared with common North American unit footprints using the ceiling height you enter. Public Storage Canada publishes an approximately eight-foot height table from 5 × 5 ft through 10 × 30 ft, while US guides commonly describe similar footprints. UK and Australian facilities frequently quote floor area in square feet or square metres and may offer different shapes. The recommendation is therefore a comparison target, not a claim that every operator sells that exact unit.
Published item-volume model
| Inventory item | Model packed volume | What to check |
|---|---|---|
| Small box | 1.5 ft³ | Use the actual external dimensions if your boxes differ. |
| Medium box | 3 ft³ | Do not assume every medium box can support heavy stacking. |
| Large box | 4.5 ft³ | Best reserved for lighter bulky contents. |
| Wardrobe box | 10 ft³ | Rail, garment length and box design change the footprint. |
| Chair | 8 ft³ | Stackability and detachable legs matter. |
| Table or desk | 35 ft³ | Measure when legs or tops cannot be removed. |
| Armchair | 25 ft³ | Recliners and wide arms often need more. |
| Sofa | 70 ft³ | Door width and longest dimension may be the limiting factor. |
| Bed or mattress set | 50 ft³ | Size, frame disassembly and safe vertical storage vary. |
| Dresser or cabinet | 35 ft³ | Do not fill furniture beyond its structural capacity. |
| Major appliance | 35 ft³ | Follow appliance preparation and position guidance. |
| Bicycle | 18 ft³ | Rack use and handlebar position change occupied space. |
These are editorial planning assumptions, not manufacturer measurements or an industry standard. For a better estimate, measure large or unusual items as length × width × height and enter the combined result under custom volume. If you replace a model item with a custom measurement, set its item count to zero to avoid counting it twice.
Why access changes the recommended size
A full cubic-volume calculation assumes perfect geometry, but real units contain irregular furniture, fragile boxes, support columns, doors and gaps. A dense 80% plan is intended for carefully stacked belongings that will remain untouched until move-out. It may require unloading much of the unit to reach the back. The 70% option leaves a modest route for occasional access. The 55% option reserves more room for a central aisle, turning space and safer retrieval.
StorageCafe advises using vertical space carefully, placing heavier furniture or boxes below lighter items and leaving a clear walkway when access matters. Do not stack higher simply because the mathematical ceiling volume exists. Box strength, falling-object risk, sprinklers, ventilation, lease rules and your ability to lift items safely can reduce usable height. Enter the facility's usable height, then choose a more conservative access mode when the stack cannot safely use it.
Common comparison sizes
| Footprint | Floor area | Volume at 8 ft |
|---|---|---|
| 5 × 5 ft | 25 ft² / 2.3 m² | 200 ft³ / 5.7 m³ |
| 5 × 10 ft | 50 ft² / 4.6 m² | 400 ft³ / 11.3 m³ |
| 7.5 × 10 ft | 75 ft² / 7.0 m² | 600 ft³ / 17.0 m³ |
| 10 × 10 ft | 100 ft² / 9.3 m² | 800 ft³ / 22.7 m³ |
| 10 × 15 ft | 150 ft² / 13.9 m² | 1,200 ft³ / 34.0 m³ |
| 10 × 20 ft | 200 ft² / 18.6 m² | 1,600 ft³ / 45.3 m³ |
| 10 × 25 ft | 250 ft² / 23.2 m² | 2,000 ft³ / 56.6 m³ |
| 10 × 30 ft | 300 ft² / 27.9 m² | 2,400 ft³ / 68.0 m³ |
The cubic figures follow the approximately eight-foot table published by Public Storage Canada. Extra Space Storage similarly describes a 10 × 20 ft unit as 200 square feet and 1,600 cubic feet. Local units can be narrower, taller, shorter, L-shaped or interrupted by building features. Compare all three dimensions and the door opening—not the marketing label alone.
Measure the items that can block the move
Before reserving, record the length, width and height of the sofa, mattress, table, appliance, shelving and any item that cannot be disassembled. Measure hallways, lifts, loading-bay clearances and unit doors. A 70 ft³ sofa does not become a flexible cube: its longest edge still has to turn through the route. Ask whether the listed unit dimensions are nominal or usable internal measurements.
Draw a simple top-down plan with the door, aisle and large-item footprints. Put belongings needed most often near the front. Leave refrigerator and freezer doors open after lawful preparation to prevent trapped moisture and odour, and follow the manufacturer's storage instructions. Never climb unstable stacks or use furniture as a ladder.
Calculate the real contract cost
An introductory offer can make the first invoice look unlike later months. This calculator discounts the entered rent for only the number of promotional months you specify. Protection or insurance, other monthly charges and one-time fees remain undiscounted. Regular monthly total is rent plus recurring charges. Contract total adds promotional and regular rent, all recurring charges for the selected term and the one-time amount. Effective monthly cost spreads that total across the term.
Enter only verified numbers from the current quote and agreement. Check whether the advertised price excludes tax, an administration fee, mandatory lock, protection plan, access charge, after-hours fee, deposit or transport. Ask how and when rent can increase, whether a promotion requires a minimum term, what notice is needed to leave, and whether a partial final month is refunded. Add known tax or transport to the one-time input only if that matches how it will be charged; the calculator does not infer local law.
Compare facilities beyond headline rent
Location, access hours, indoor or drive-up access, lift availability, loading distance, climate control, lighting, cameras, individual alarms and staff presence can affect value. Protection terms may exclude certain causes, item types or maximum values. Read the contract and policy rather than treating a security feature or the word “insurance” as a guarantee.
Climate control may matter for temperature- or humidity-sensitive belongings, but advertised conditions and monitoring differ. Ask for the operating range and exclusions. Confirm whether pallets, shelving, vehicles, food, plants, batteries, fuel, chemicals, pressurised containers, weapons, controlled goods or business inventory are allowed. Never store people, animals, illegal goods, hazardous materials or anything prohibited by the agreement or local law.
Use an inventory before signing
Number boxes and keep a private inventory with photos, approximate value and the unit location of important items. Do not put sensitive descriptions on the outside of cartons. Back up the inventory somewhere separate from the unit. Consider whether replacement value justifies storage cost over the full expected term; donating, selling or recycling low-value items can reduce both unit size and long-term rent.
Visit the actual unit where possible. Confirm it is dry, clean, accessible and the size quoted. Test the route with the largest item. If the inventory estimate sits close to a capacity boundary, choose the safer layout or pack a representative group first. A slightly smaller unit is not a saving if belongings cannot be retrieved safely or are damaged by forced stacking.
Current planning references
- Extra Space Storage unit size guide — compares common US footprints and describes a 10 × 20 ft unit as 200 square feet and 1,600 cubic feet.
- StorageCafe size calculator and guide — recommends measuring large items, allowing for boxes and leaving a walkway when access matters.
- Public Storage Canada calculator — uses item quantities and dimensions and publishes an approximate eight-foot-high capacity table.
- Shurgard UK size calculator — demonstrates local size-search and quote intent using postcode or city.
- Storage King Australia space estimator — demonstrates Australian demand for choosing space for household and business storage.
Frequently asked questions
Should I choose floor area or cubic capacity?
Use both. Cubic capacity helps estimate stacked volume, while floor shape, door width and long-item dimensions determine whether belongings can physically enter and be arranged.
Can I rely on a bedroom-based storage guide?
Use it only as a rough cross-check. Two homes with the same bedroom count can have very different furniture, storage areas and box totals. An inventory-based estimate exposes more of the assumptions.
Does a 50% first-month offer halve my contract cost?
No. It halves entered rent for the specified promotional month only. Later rent and all entered recurring and one-time charges remain in the total.
Does the suggested size guarantee availability?
No. Availability, dimensions and names differ by facility. Use the result as a target when requesting current local quotes and confirm the actual unit before committing.
This calculator is independent and currently contains no storage-provider affiliate links or paid placements. It does not promise an exact fit, price, secure facility or lower bill. Future commercial relationships will be clearly labeled and will not change the published model or editorial criteria.