Warehouse money rarely leaves through one big hole. It leaks: a few seconds per pick, a pallet position paid for and half empty, a return handled twice, safety stock set by feel instead of by demand variation. None of it shows up as a line in the P&L called "waste". It shows up as a margin that is always slightly worse than the plan.
The fastest way to find those leaks is to put actual numbers on them. Below are fourteen numbers worth knowing about your own operation — grouped the way warehouses actually think: space and transport, stock and ordering, labour and cost. For each one: what it measures, what a healthy value tends to look like, and what a bad value usually means. Every one has a free calculator, no account needed.
In short
- Cost per order line is the single most revealing number in a warehouse. If you only calculate one, calculate that.
- Picks per hour and labour requirement tell you whether your peak plan is realistic or a hope.
- Safety stock, reorder point and EOQ decide how much cash sits still on your floor.
- Storage cost per pallet and racking layout tell you whether you need a bigger building or a better one.
- A bad number is not a verdict. It is a starting point for the question "why".
Group 1 — Space and transport
Space is a fixed cost you pay every month whether you use it well or not. Transport is a variable cost that is quietly priced on air.
1. Pallets and load metres per shipment
How many pallets fit on the truck, and how many load metres you are actually paying for. Carriers charge by the metre, so a half-built pallet is a metre you bought and did not use. If your average shipment fills fewer load metres than you are invoiced for, the gap is money. Pallet and load metre calculator.
2. Volumetric weight
Parcel carriers bill on whichever is greater: actual weight or volume-derived weight. Light, bulky goods almost always bill on volume. If you have never compared the two for your top-selling boxes, you are very likely paying for air on every parcel. Volumetric weight calculator.
3. Warehouse space needed
How many square metres your stock and your aisles actually require. Most operations discover they need less building and better layout. A move is the most expensive answer to a storage problem, and often the wrong one. Warehouse space calculator.
4. Racking layout
How many pallet positions a given floor area yields at a given aisle width and rack height. Narrowing aisles or adding a beam level typically buys more positions than most managers expect — and far cheaper than a second site. Racking layout calculator.
5. Container loading
How many cartons genuinely fit in a 20ft or 40ft container. Ordering a container that ships at 80% utilisation means paying full freight for a partly empty box, every time. Container loading calculator.
Group 2 — Stock and ordering
Stock is cash you have already spent, sitting still. Too little and you disappoint customers; too much and you finance a warehouse full of decisions made months ago.
6. Safety stock
The buffer that absorbs demand variation and supplier lateness. Set by gut feeling it is almost always too high on slow movers and too low on fast ones — the worst combination, because you pay for stock you don't sell and stock out on the items you do. Safety stock calculator.
7. Reorder point
The stock level at which you place the next order. If your reorder points were set when lead times were shorter, every one of them is now wrong in the same direction. Reorder point calculator.
8. Economic order quantity (EOQ)
The order size that balances the cost of ordering against the cost of holding. Frequent small orders drive admin and inbound handling; large orders tie up cash and space. EOQ is the midpoint between those two bills. EOQ calculator.
9. Cycle count workload
How many counts per day keep your stock accuracy honest without a full annual shutdown. Warehouses that count continuously stop having stock-take weekends — and stop discovering discrepancies months after they happened. Cycle count calculator.
Group 3 — Labour and cost
Labour is usually the largest controllable cost in a warehouse, and the one most often planned on last year's assumptions.
10. Picks per hour
Your real picking rate, per picker, per hour. Paper picking, single-order picking and long walking routes all show up here. Batch picking and scan-directed routing are the usual step change. Picks per hour calculator.
11. Labour requirement
How many people you need to clear a given volume within your cut-off. Do this for peak, not for an average week — the average week never breaks anyone. Warehouse labour calculator.
12. Storage cost per pallet
Rent, energy, racking and handling divided by usable pallet positions. This is what a pallet position costs you per week — and what a slow-moving SKU is quietly charging your margin. Pallet storage cost calculator.
13. Cost per order line
Total warehouse cost divided by order lines shipped. The most revealing number in the building: it moves when anything real changes, and it is the number a WMS business case ultimately has to shift. Cost per order line calculator.
14. Cost of returns
What one return actually costs once you count inspection, repack, restock, write-off and the original outbound shipping. In ecommerce this is routinely several times what people assume, and it is rarely on anyone's dashboard. Returns cost calculator.
The fourteen at a glance
| Number | What a bad value usually means |
|---|---|
| Pallets / load metres | Paying for metres you don't fill |
| Volumetric weight | Parcel spend priced on air |
| Warehouse space | Layout problem misread as a space problem |
| Racking layout | Positions left on the table at current height |
| Container loading | Full freight for a partly empty container |
| Safety stock | Cash in slow movers, stockouts on fast ones |
| Reorder point | Reorder levels built on old lead times |
| EOQ | Ordering rhythm set by habit, not cost |
| Cycle counts | Discrepancies found months too late |
| Picks per hour | Walking and paper, not picking |
| Labour requirement | Peak plan based on an average week |
| Storage cost per pallet | Dead stock charging your margin rent |
| Cost per order line | Every inefficiency, added up |
| Cost of returns | A cost centre nobody owns |
What to do with a bad number
A single bad number is a symptom, not a diagnosis. The useful sequence is: calculate it, compare it to the same number six months ago, then ask which process produces it. Picks per hour is produced by pick paths and pick method. Cost per order line is produced by everything at once. Returns cost is produced by what happens in the first ten minutes after a parcel comes back through the door.
Where these numbers repeatedly point at the same thing — people walking, stock that is not where the system says, decisions made on yesterday's data — the answer is usually not more staff. It is process control: scan-directed work, one stock truth, and exceptions that surface while they can still be fixed. That is what a warehouse management system is for, and the honest way to test it is against your own numbers rather than a vendor's averages.
Frequently asked
Do I need all fourteen? No. Start with cost per order line, picks per hour, and storage cost per pallet. Those three explain most of what happens to warehouse margin.
What if I don't have the input data? Estimate it. An approximate number you act on beats an exact number you never produce. Each calculator explains where to find the input and what a typical value looks like.
How often should these be recalculated? Quarterly for stock settings, monthly for labour and cost, and always before a peak season or a system decision.
Are the calculators free? Yes — all fourteen, no account required. See the full set on the warehouse calculators page, and read the plain-English WMS guide if the numbers point at process rather than people.
