Guide · updated
Bigger units cost less per square foot
The smallest unit costs $1.36 per square foot. The largest costs $0.69 — 49% less for the same cubic space.
Every unit carries the same fixed overheads: a door, a lock, a slice of corridor, a line in the security system, the staff time to rent it. Those costs barely change between a locker and a garage, so they land far more heavily on a small unit. The result is a price curve that falls steadily with size.
- 5x5 · 25 sq ft $1.36
- 5x10 · 50 sq ft $1.08
- 5x15 · 75 sq ft $1.00
- 10x10 · 100 sq ft $0.94
- 10x15 · 150 sq ft $0.79
- 10x20 · 200 sq ft $0.74
- 10x25 · 250 sq ft $0.66
- 10x30 · 300 sq ft $0.69
| Size | Sq ft | Observations | Typical monthly | Per sq ft |
|---|---|---|---|---|
| 5x5 | 25 | 23,412 | $34 | $1.36 |
| 5x10 | 50 | 30,586 | $54 | $1.08 |
| 5x15 | 75 | 12,455 | $75 | $1.00 |
| 10x10 | 100 | 30,289 | $94 | $0.94 |
| 10x15 | 150 | 21,184 | $118 | $0.79 |
| 10x20 | 200 | 20,769 | $149 | $0.74 |
| 10x25 | 250 | 6,680 | $165 | $0.66 |
| 10x30 | 300 | 11,393 | $208 | $0.69 |
Where the trend breaks. It is not perfectly monotonic: the 10x30 costs more per square foot than the size below it. The likely reason is supply — the largest units are rare, held by fewer facilities, and scarcity outweighs the overhead effect. We are reporting it rather than smoothing it, because a curve that is clean everywhere usually means someone cleaned it.
The national curve is not your market
Everything above is measured across the whole country, and at that scale the rule looks like a law. It is not one. Of the 238 markets holding four or more sizes, 148 — 62% — contain at least one step where the larger unit costs more per square foot than the size below it, not less.
The reason is the same one that breaks the national curve, only sharper locally: the big units are rare. A market may hold forty 5x5 lockers and four 10x30 garages, and four of anything price on scarcity rather than on overheads. Where that happens the per-foot argument reverses, and renting up costs more per foot as well as more in total.
| Market | Step | Smaller, per sq ft | Larger, per sq ft | Penalty |
|---|---|---|---|---|
| Tucson, AZ | 10x25 → 10x30 | $0.35 | $0.92 | +165% |
| Gainesville, VA | 10x20 → 10x25 | $0.50 | $1.05 | +109% |
| Crestview, FL | 5x5 → 5x10 | $0.32 | $0.60 | +88% |
| Gainesville, VA | 5x5 → 5x10 | $0.52 | $0.96 | +85% |
| Beaumont, TX | 10x20 → 10x30 | $0.54 | $0.99 | +83% |
| Titusville, FL | 5x15 → 10x10 | $0.49 | $0.90 | +82% |
| Myrtle Beach, SC | 10x20 → 10x30 | $0.66 | $1.16 | +75% |
| Santa Rosa Beach, FL | 5x15 → 10x10 | $0.41 | $0.70 | +69% |
So check your own market before renting up on this argument. Every market page carries its own per-square-foot column, computed the same way as the table above.
How to use this. The per-square-foot figure is not a reason to rent a bigger unit than you need — paying more in total for a lower unit rate is still paying more. It is a reason to check the next size up when you are close to the boundary. Going from 5x5 to 5x10 doubles your space for 59% more money, which is the single best value step in the range.
It is also a reason to be suspicious of splitting your belongings across two small units. Two 5x5 units cost more than one 5x10 and give you the same floor area, two doors to unlock and two sets of paperwork.