Most chip shops never do a proper stocktake, and it is easy to see why. The only sensible time to count is the one time you cannot: service. So it gets pushed to next week, then to the week after, and by the time anyone looks at the numbers the fish has been eaten and the explanation has gone with it. The fix is not a bigger spreadsheet. It is a smaller routine, done at a time that suits the fryers instead of fighting them. Thirty minutes, once a month, four things counted properly: fish, chips, oil and packaging.

Why a monthly count beats an ambitious weekly one

Chip shop stock splits into two kinds. Fish moves fast and costs the most per item, so it is the line most likely to drift without anyone noticing. Packaging and oil sit in cupboards and drums and barely change from one week to the next.

Counting everything every week burns goodwill and gets abandoned by the second month. Once a month is frequent enough to catch a problem before it becomes a habit, and rare enough that nobody dreads it. If you want something weekly, make it the fish count: five minutes, one number, written on the same sheet every time.

Choose the slot before you print the sheet

Tuesday to Thursday, early afternoon, is the natural window for most shops. The lunch trade has gone, the tea-time rush has not started, and the fryers are either idle or settling. Monday works too if you close. What matters less is the day and more that it is the same day every month, in the diary, with a name next to it.

Two other rules. Do not count on a delivery morning before the stock is put away; half your answers will still be on a pallet in the doorway. And measure oil under the same conditions every time. Hot or cold does not matter much, as long as it is consistent. If you read the dipstick with the fryer at temperature in month one, read it at temperature in month two.

Then decide who does it. One person counts, one writes. If the person who orders the stock is the only person who counts it, mistakes have nowhere to show up. Two sets of eyes on five boxes of cod takes thirty seconds.

The 30-minute count, item by item

With the sheet printed and the paperwork to hand, work in this order. High value first, awkward items last.

• Fish — 8 minutes. Count by type: cod, haddock, scampi, whatever you carry. Write the number on the lid of any part box, along with the date. Do not weigh individual fillets. An honest estimate of a half-full box, written down, beats an exact count you will never finish. Keep frozen and fresh on separate lines; they carry different values and different waste rates.
• Potatoes and chips — 5 minutes. Full sacks, plus a fraction for anything opened. A sack two-thirds full is 0.67 on the sheet, not "nearly full". If you fry frozen chips, count bags and part bags the same way.
• Oil — 5 minutes. Fryer contents, plus closed drums, plus any part drum. Dipsticks and marked drums both work. Note the date you last filtered and the date of your last collection.
• Packaging — 7 minutes. Count sleeves and boxes, not individual items, then multiply. A box of 500 chip boxes is one number, not five hundred. Write part-box estimates on the flap.
• Paperwork — 5 minutes. Gather delivery notes, credit notes for anything returned, and the waste sheet. This is the part people skip, and it is the part that makes the arithmetic mean anything.

The only formula you need

Opening stock plus purchases, minus closing stock, equals usage. Everything after that is just asking why.

Compare usage to what your sales say you should have used. That comparison is the whole point of the exercise.

A fish example

Say you sold 400 cod over the month and one fillet goes out per portion. Expected usage: 400 fillets. The formula says 465. That is 65 fillets of daylight. Before you suspect anyone of anything, check the ordinary explanations: a delivery signed for but never entered on the sheet, fillets that arrived smaller and got doubled up, a batch binned and not recorded, staff meals, or a short delivery you did not open until it mattered. Most gaps are paperwork, not people.

Calibrating your chips

Chip usage is impossible to control until you know your own yield. Weigh out one kilo of chipped potatoes and count the portions. Do it once, on a normal day, at normal portion size. Now you have a number: portions per kilo. Multiply your monthly portion sales by that, and you know roughly how many kilos should have left the store. Compare it to the formula. If you sell chips by weight rather than by portion, weigh the same sample and work in grams instead.

Which variances are worth chasing

Not every difference deserves a meeting. Rank them.

• Fish out by more than a few per cent. Small and steady is usually portion size. Sudden and large is usually a missing delivery note.
• Oil running high. Check filtering frequency, how used oil is disposed of, whether fryers are running hotter than they need to, and whether anyone tops up from a drum nobody is recording.
• Packaging high. Nearly always overpacking. Bags for small orders, double boxing, a stack of forks by the till that goes out with everything. Watch one service and you will see it.
• Chips. The giveaway bag. Ten extra bags a day is a real number over a month.

Small, consistent differences are normal in a kitchen. You are looking for changes, not perfection.

Habits that keep the monthly count honestPhoto: cottonbro studio / Pexels