BUYING STOCK / PRACTICAL GUIDE

When bulk buying stops being a bargain.

Compare what you pay with what you expect to sell. The cheapest advertised unit price is only the starting point.

SphereCraft Tools · Updated 19 October 2026 · Illustrative examples

Start with the full delivered cost

A supplier offers 100 individually sold chews for £40. That looks like 40p each. An £8 delivery charge makes the delivered batch cost £48, or 48p each. Adding a 5p bag or label allocation makes it 53p before wastage. Enter each expense once: including delivery in both your stock cost and another cost field would overstate it.

Spread the cost over the stock you can sell

Suppose five chews from that batch will be damaged or pass their selling date before sale. You still paid £48 for the delivered batch, but now expect to sell 95. The stock cost per sellable chew becomes £48 ÷ 95 = roughly 50.53p. With 5p packing per sellable chew, your included unit cost is about 55.53p.

This example assumes packing is used only for stock sold. If you pack everything before discovering a loss, include the wasted packing in the batch cost too, rather than pretending it disappears.

Compare the larger order on the same basis

A second supplier offers 150 similar chews for £66 with free delivery. At 44p each before packing, it initially beats the first supplier’s 48p delivered stock cost. But if slower turnover or shorter shelf life means 15% wastage, expected sellable stock is 127.5 chews. That fractional figure is a planning average across batches, not half a physical chew to sell.

The first supplier is now about 1.24p cheaper per sellable chew. The difference is small, and the wastage assumptions drive it. Try different wastage estimates in the calculator before treating either offer as better value.

Check how much wastage changes the decision

Keeping supplier A at 5% wastage, supplier B reaches approximately the same unit cost at 12.92% wastage. Below that level B is cheaper per sellable chew on the stated costs; above it A is cheaper. If your records do not support a reliable estimate, compare several scenarios rather than selecting a convenient percentage.

For loose food, compare the same weight

For a 12.5 kg bag costing £20 plus £5 delivery, with 4% expected wastage, sellable weight is 12 kg. The delivered stock cost is £25 ÷ 12, or about £2.0833 per sellable kilogram. A 500 g portion uses about £1.0417 of stock before its bag, label or other selling costs. Use kilograms for both suppliers and keep packaging allocations consistent.

Keep the cash commitment visible

Unit cost does not answer how much cash you can afford to tie up. In the chew comparison, the second order requires £66 for stock and delivery instead of £48. Check how long the extra stock will take to sell, what storage it needs and whether you need that cash for other products. These factors matter even if the larger pack wins on cost.

A quick buying routine

1. Match product quality, pack quantity and units.
2. Use actual discounted pack prices and allocate delivery once.
3. Estimate wastage from damage, expiry and your own sales history.
4. Include packing at the stage where you incur it.
5. Compare sellable unit costs, then check the total cash needed.
6. Use the margin calculator to assess a selling price, including any costs still missing.

These examples are buying estimates. They do not calculate tax, demand or business net profit. Keep the same cost basis across the comparison and use actual invoices and stock records when available.