How to use it
Three steps.
Enter your opening stockThe value of the stock you held at the start of the period, measured at cost.
Add purchases and closing stockStock bought during the period, then the value remaining at the end. Opening stock + Purchases − Closing stock = Cost of sales
Enter your net salesSales excluding VAT, for the same period and department. You get your actual GP, the gap to target in pounds, and days of stock on hand.
A worked example
One month in a restaurant.
| Opening food stock | £4,000 |
| Food purchases | £2,000 |
| Closing food stock | £3,000 |
| Cost of sales | £3,000 |
| Net food sales | £10,000 |
| Gross profit | £7,000 |
| Gross profit percentage | 70% |
This is the GP established from your stock movement, not a theoretical margin based on menu prices.
The common mistake
Trusting the till.
An EPOS system can produce an impressive looking margin report. But what if the cost prices were never loaded? At one independent hotel I found exactly that, and its historical margin figures couldn't be relied upon.
A stock based calculation is only as good as the figures entered: accurate counts, purchases recorded correctly, and opening and closing stock valued the same way. Transfers and other adjustments may need accounting for too.
Why regular stocktakes matter
The pattern, not just the percentage.
One count gives you a starting point. Regular counts show whether your margins are improving, whether stock levels are sensible and where discrepancies are developing.
Other free tools
Check another number.
GP & menu price
Your real GP on one dish or drink, the price to hit your target, and what a supplier rise does to it.
Full page & worked example →Stock based GP
Your actual GP from opening stock, purchases, closing stock and net sales, with the gap in pounds.
You are herePour cost & bottle yield
Serves per bottle, cost per serve and what over pouring costs you a year.
Full page & worked example →