Warehouse Space & Racking Calculator
How many pallet positions a floor area will actually hold — after aisles, cross-aisles, staging and the clear height you really have. The number that comes out of this is usually 30–40% below the one in the landlord's brochure, and that gap is the whole point.
Your data never leaves your browser — everything is calculated on your device.Why the brochure number is always wrong
A 50,000 sq ft warehouse does not store 50,000 sq ft of pallets. Working down from gross area:
- Dock and staging takes 12–18%. This is the deduction most often forgotten, and it is permanent — goods have to land somewhere before they are put away.
- Office, amenities, QC and charging bays take another 5–8%.
- Aisles and cross-aisles take 55–65% of what remains under selective racking — two 1.2 m rack rows for every 3.3 m aisle, before cross-aisles and flue space. This is where the racking decision actually bites.
- What is left is the rack footprint — typically 28–35% of the gross area in a selective-racked distribution warehouse.
Then multiply by beam levels, which is where clear height turns into capacity. Every additional metre of usable height is nearly free capacity compared to taking more floor.
Density and selectivity pull against each other
Drive-in racking can hold 60–70% more pallets in the same footprint than selective — but you can only reach the front pallet of each lane, so it works only where you have many pallets of the same SKU and can live with last-in-first-out. Choosing drive-in for a broad, slow-moving catalogue produces a dense warehouse that nobody can pick from. The comparison table above shows the trade for your own numbers; the right answer depends on how many SKUs you have per lane, not on which system stores the most.
Common mistakes
- Using ridge height instead of clear height. Sprinklers, haunch, lighting and ducting all sit below the ridge. Design to the lowest obstruction over the racking run, not the highest point of the roof.
- Forgetting the top-beam clearance. Fire regulations and sprinkler design require clearance between the top of the load and the sprinkler head — typically 450–900 mm. Planning to the roof and discovering this at commissioning is an expensive way to learn it.
- Assuming 100% occupancy. A warehouse running at 100% of pallet positions cannot operate: no room to consolidate, no room to receive, every put-away becomes a search. Design for 85–90% and treat anything above that as a warning.
- Ignoring floor flatness and loading. VNA in particular needs a superflat floor (FM2 or better) and adequate point loading. Retrofitting that into an existing shed costs more than the racking.
- Sizing to today's pallet. If half the inbound arrives on 1200×800 pallets and the racking is set for 1200×1000, capacity and stability both suffer. Standardise first, then design.
Questions people ask
How many positions should a good warehouse achieve per 1,000 sq ft?
For selective racking at around 32 ft clear height, roughly 100–130 positions per 1,000 sq ft is a reasonable range — about one position for every 8–10 sq ft of gross area. Below 75 suggests low clear height, generous aisles, or a lot of the building lost to non-storage use. Above 160 usually means a denser system than selective, so check what it has cost you in selectivity.
Does this include mezzanine or shelving areas?
No — it works in pallet positions only. Small-parts shelving, mezzanine picking faces and bin locations need separate sizing, and in a spare-parts operation they often matter more than the pallet racking does.
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