Hong Life CalculatorsUnderstanding the self storage unit size and cost calculator — concept and principle
When you move, renovate, travel or downsize, a self storage unit can hold furniture until you need it again. The two questions are how big a unit you need and what it will cost over the time you rent it. This calculator suggests a floor area from the number of furnished rooms and multiplies it by the price per square metre and the number of months.
How it is calculated
- Suggested unit (m²) = rooms of furniture × 3.5.
- Total cost = suggested area × price per m² per month × months.
The price is per square metre of floor area per month in your currency. If your provider quotes a price per unit instead, divide it by the unit's area to compare offers.
The principle
The 3.5 m² per room figure is a rule of thumb sitting in the middle of the commonly quoted 3–4 m² of floor for the contents of one furnished room, assuming items are stacked to a normal height and packed in boxes. Storage is priced by floor area because that is what the provider can rent out, so cost scales in direct proportion to area and time. The real space you need depends on volume, not floor area: a unit with a high ceiling lets you stack more, while bulky items such as sofas and wardrobes take more floor than boxes.
Worked example
- Inputs: 2 rooms of furniture, $25 per m² per month, 6 months.
- Suggested unit: 2 × 3.5 = 7 m².
- Monthly cost: 7 × 25 = $175.
- Total cost: 175 × 6 = $1,050.00.
| Rooms of furniture | Suggested unit (m²) |
|---|---|
| 0.5 | 1.75 |
| 1 | 3.5 |
| 1.5 | 5.25 |
| 2 | 7 |
| 2.5 | 8.75 |
| 3 | 10.5 |
| 4 | 14 |
How to read the result
Treat the suggested area as a starting point and match it to the nearest unit size your provider offers. Choosing one size too small can mean items do not fit on moving day; choosing too large wastes money every month. Price per m² usually falls for larger units and long contracts, and many providers offer introductory discounts, so compare the full-term total, not just the first month. If storage will last many months, compare the total with the cost of simply selling and later replacing low-value furniture.
Common mistakes
- Forgetting access space: leave an aisle so you can reach items at the back.
- Counting rooms but not garages, sheds or garden furniture.
- Ignoring insurance, locks and admin fees.
- Using a promotional first-month price for the whole rental.
Frequently asked questions
How do I convert to square feet?
1 m² is about 10.76 sq ft, so 7 m² is about 75 sq ft.
Does ceiling height matter?
Yes. Volume is what you fill; a taller unit lets a smaller floor area hold more if items can be safely stacked.
Can I store anything?
No. Providers prohibit items such as flammable liquids, gas cylinders and perishable food; check their list.
Sources: Self Storage Association UK (SSA UK) — Annual Industry Report