An actual food-cost percentage comes from stock and invoices. A theoretical food-cost percentage comes from what your recipes say should have been used. You need both because they answer different questions.
actual usage = opening stock + purchases − closing stock
actual food cost % = actual usage cost ÷ food sales × 100
Theoretical usage is calculated from sales and recipe quantities. Comparing actual with theoretical helps you find where the operation is losing margin, but it does not prove the cause on its own.
Choose a start and end time, then count opening and closing stock on the same basis. Use the same units and valuation method for both counts. A weekly count taken at different times around deliveries can create a variance that looks like waste but is really a timing mismatch.
Record purchases that belong inside the period, including credits and substitutions. Keep invoices and count sheets tied to the same date range. If one supplier invoice arrives late, flag it rather than silently moving it into a different week.
Suppose the opening stock is valued at £2,400, purchases during the period total £5,100, and closing stock is £2,150:
actual usage = £2,400 + £5,100 − £2,150 = £5,350
If food sales for the same period are £17,000, the actual food-cost percentage is £5,350 ÷ £17,000 × 100 = 31.47%. Keep the full precision in the working sheet and round only for the report.
That example is illustrative. The calculation is only as reliable as the stock valuation, purchase capture and sales denominator underneath it.
For each sold dish, multiply the recipe quantity by the number sold. Add the ingredient costs for every dish and compare the result with actual usage. A difference can come from portioning, waste, staff food, unrecorded transfers, receiving errors, price changes, recipe changes or counting mistakes.
Start with the largest variances by value. Check the physical process before blaming a person: portion tools, prep yields, waste recording, recipe versions and delivery timing often explain more than a single spreadsheet cell.
If actual cost is higher than theoretical cost, ask:
1. Did the stock count use the same units and valuation method?
2. Were all purchases and credits recorded in the same period?
3. Did supplier prices or pack sizes change?
4. Are portions and yields still the same as the recipe?
5. Were waste, staff meals, transfers and comps recorded?
If theoretical cost is higher than actual, check whether the sales mix, recipe version or count timing is wrong before treating it as a win.
Use a stable item list, clear units, a count order that follows the kitchen, and a place to record notes. Review the same variance categories every period. A stock-take sheet is useful when it reduces the number of decisions the team has to make while counting; it is not useful if it creates a second unofficial list.
The PrepSheet stock-take template collection is designed for repeat counts, while the free food cost calculator checks the dish-level assumptions behind theoretical cost.