A box of fish is bought by a batch or weight, a sack of potatoes loses peel and trim, and a takeaway meal needs more than those two ingredients. Build the cost from the purchase unit through to the portion you actually serve. Keep each allowance visible so it can be checked against your own records.
Divide the fish purchase cost by saleable portions
For this example, a batch of 20 fillets costs £40. We assume one whole fillet is used for each meal. A separate 5% allowance for fillets lost before sale leaves 19 saleable fillets:
20 fillets × (1 − 5%) = 19 saleable fillets
£40 ÷ 19 = £2.105263 per saleable fish portion
The fish cost rounds to £2.11 for display. The calculation retains its unrounded value when adding the meal cost. If your fish is purchased by weight, establish the actual fillet count or measured portion weight first. A count alone cannot tell you how much fish a large portion contains.
The 5% here is an explicit loss assumption, not something the POS measures. If the purchase already contains only saleable portions, do not deduct the same loss again. Record actual rejected, spoiled or otherwise lost fish to replace the assumption over time.
Use prepared, pre-fry potato weight throughout
Assume a 25 kg raw potato sack costs £15. After peeling and trimming, an illustrative 80% preparation yield gives 20 kg of prepared potato. A further, separate 5% loss leaves 19 kg available for portions. Each example meal uses 300 g of that prepared potato before frying.
25 kg raw × 80% preparation yield = 20 kg prepared
20 kg × (1 − 5% further loss) = 19 kg usable, pre-fry potato
£15 ÷ 19 kg × 0.300 kg per portion = £0.236842
That is £0.24 of potato per example portion after rounding. The 80% yield already accounts for peeling and trimming; the extra 5% must represent a different loss. If your measured preparation yield includes all those losses, do not apply them again.
Do not weigh cooked chips at 300 g and put that number into this pre-fry calculation. Frying changes the weight basis. Either measure the prepared pre-fry potato allocated to a portion, or establish your own measured conversion between that quantity and the cooked serving. Oil uptake is not measured by this worksheet.
Add the rest of the meal
The selected meal also includes an illustrative £0.14 of batter, £0.12 allocated for frying oil, a £0.22 side and £0.25 of packaging. These are separate per-portion inputs:
| Input | Illustrative value |
|---|---|
| Fish pack cost | £40.00 |
| Comparable fillets in the purchased pack | 20 fillets |
| Further unsaleable fillets, not already excluded | 5 % |
| Raw potato sack cost | £15.00 |
| Raw potato sack weight | 25 kg |
| Preparation yield: prepared weight ÷ raw weight | 80 % |
| Further potato loss, not already in preparation yield | 5 % |
| Prepared potato per portion, before frying | 300 g |
| Batter allowance per portion | £0.14 |
| Allocated frying oil cost per portion | £0.12 |
| Selected side per portion | £0.22 |
| Packaging per portion | £0.25 |
20 fillets × 95% = 19 saleable fillets; £40 ÷ 19 = £2.105263… each. For potatoes, 25 kg × 80% × 95% = 19 kg usable prepared potato, before frying. A 300 g prepared portion costs £15 × 300 ÷ 19,000 = £0.236842…. The 5% further loss is separate from preparation yield.
| Component | Example cost |
|---|---|
| One saleable fillet | £2.11 |
| Prepared potato | £0.24 |
| Batter allowance per portion | £0.14 |
| Allocated frying oil cost per portion | £0.12 |
| Selected side per portion | £0.22 |
| Packaging per portion | £0.25 |
| Food and packaging total | £3.07 |
The total uses unrounded component costs; individual rows are rounded to the nearest penny. Labour, energy, rent, equipment, payment processing, marketplace charges and other unlisted costs are excluded. This is not net profit.
Adding the unrounded fish and potato costs to those four inputs gives £3.072105, displayed as £3.07. Adding already rounded line values can produce a different penny total; retain the calculation values until the end.
The oil input is an allocation, not actual measured oil consumption. To replace it, choose a documented allocation method, such as the cost of oil used over a recorded period, allocated across the relevant portions, with waste and other fryer products accounted for. Avoid counting oil twice through both batter costing and a separate allowance.
The £3.07 estimate covers only the listed items. Add any seasoning, condiments or other consumables not already included in their inputs. Confirm the contents and purchase cost of each side pot and packaging item; a meal with no side or different packaging needs a different input.
Use your invoices, fillet counts and a measured potato preparation batch. Enter a zero only when the item is genuinely known to add no cost; leave unconfirmed values blank. An unknown input prevents a complete total.
Calculate your portion cost
Start with your own measurements, or load the labelled illustrative example. Leave an unknown value blank. Enter 0 only when you have established that there is no cost or additional loss for that input.
Values stay in this page’s memory. This worksheet does not save to the POS, use browser storage or send your entries anywhere.
Portion cost unknown. Enable JavaScript to calculate your inputs; blanks are not zero.
The result is an estimate from the values entered on this page. It does not save a recipe, adjust inventory or establish the full cost of trading. Keep fish counts, potato yield and serving weights on the bases explained above.
Check the ingredient units and product recipe
Where inventory and recipes are enabled in POSMENTOR, check each stock item’s unit and purchase price before linking it to a product. A per-fillet calculation needs a compatible count-based setup or a verified conversion; it should not be copied unchanged into a kilogram price field. Potatoes, batter and sides need their own consistent quantities and units.
Decide where each loss allowance is represented. If you have already increased a recipe quantity or adjusted an ingredient cost for that loss, applying the same factor again would overstate the cost. Keep the assumption documented alongside the recipe rather than assuming the system measures it.
Check regular and large fish meals separately. Review how configured options affect the recipe; an option label or a preparation note does not prove the corresponding stock quantity will change. Completed orders drive consumption from configured recipes, so missing or incorrect recipes can make expected use misleading.
An incomplete recipe, unverified ingredient price or incompatible unit leaves the full cost unknown. Do not turn a missing value into a free ingredient. Review inventory and recipe costing and the fish and chips menu setup guide together.
Compare expected use with the shop’s records
For a chosen period, compare recipe-based usage with actual counts and recorded waste. Investigate differences in fish counts, trimming, portion weights, unsold food and unrecorded meals. A calculated allowance is a starting assumption, not proof of what happened in the fryer or stockroom.
These ingredient and packaging costs are not net profit. Labour, energy, rent, equipment, payment fees, delivery commissions and other relevant costs still need consideration. Keep a consistent basis for the costs you compare; this guide does not calculate tax or recommend a selling price.
Bring one purchase invoice, a measured potato preparation batch and one meal recipe to a demo. Ask to see the stock units, recipe cost and configured completed-order consumption in a demonstration account. This guide itself did not create orders or stock movements to test those behaviours.
Continue with the fish and chips shop POS overview, ordering choices or the wider takeaway workflow.
Discuss fish and chips recipe costing
Keep a reusable costing workspace
Keep your fish, potato and packaging entries in the standalone Chrome calculator. Record your own preparation yields and portion quantities; the tool does not measure fryer oil use or waste for you.
Explore POSMENTOR Recipe Cost for Chrome. No POSMENTOR account required; data stays in your Chrome profile and is not automatically transferred to the POS.