Practical advice for costing your dishes accurately in a real kitchen environment.
Calculating an accurate food cost sounds simple — list your ingredients, find the prices, add them up. But in a real kitchen environment, there are numerous factors that can cause your actual costs to differ significantly from your theoretical estimates. This guide covers the most common pitfalls and how to avoid them.
One of the most common costing mistakes is calculating ingredient cost based on the weight you use in the dish, rather than the weight you need to purchase to get that amount.
You need 180g of chicken breast per portion.
After trimming fat and removing sinew, a raw chicken breast yields approximately 85% edible meat.
To get 180g of usable chicken, you need to purchase: 180g ÷ 0.85 = 212g
If chicken costs £8.50/kg, your real cost is 212g × £0.0085 = £1.80, not £1.53.
Keep a reference sheet of yield percentages for your most commonly used ingredients — meat, fish, vegetables. Weigh your trim and calculate the yield once, then use it consistently in all your costings.
Many ingredients lose weight during cooking. Meat loses 20–30% of its weight when roasted or grilled. Vegetables shrink when sautéed. Stocks reduce significantly during simmering. If you don't account for cooking loss, your cost per gram of finished product is higher than you think.
For key proteins on your menu, weigh the ingredient before and after cooking to establish your cooking loss percentage. Factor this into your recipe cost alongside prep yield.
Oil, salt, pepper, herbs, butter for finishing — these seem negligible individually but add up across hundreds of dishes. A dish using 5ml of olive oil, a knob of butter, and fresh herbs might add 15–25p to your cost. On a £9 dish with a 30% target food cost, every penny matters.
For seasonings and finishing ingredients that are difficult to measure precisely, add a fixed sundries amount (typically £0.10–£0.20) to every dish cost as a catch-all for small items.
If you buy from a wholesale supplier, your ingredient costs will be significantly lower than supermarket retail prices — but if you buy from a supermarket (for top-ups or lower volume), your costs will be higher. Always use the price you actually pay.
If your supplier prices vary by order quantity, cost using your typical order size rather than the best possible price.
Ingredient prices fluctuate. A recipe costed six months ago may be significantly more or less expensive today. Build a habit of reviewing your costings whenever you receive a supplier price notification or at least quarterly.
Key practice: Flag any dish where the ingredient cost has increased by more than 10% since you last set the price. These dishes may need repricing or reformulating.
Portion creep is a real problem in busy kitchens. Over time, chefs may unconsciously serve slightly larger portions, increasing your food cost without any change to your menu price. Standardise your portion sizes with specific weights and train your kitchen team to use them consistently.
Spot-check portion weights periodically. A 20g over-portion on a protein dish across 50 covers per day costs you significantly more than you might expect over a month.
If you run a takeaway or delivery operation, packaging — boxes, bags, napkins, sauces — adds real cost to every order. Include packaging costs in your takeaway dish costings, especially as packaging costs have risen considerably in recent years.
Use our free calculator to cost your dishes accurately — enter ingredients, portions, and supplier costs in minutes.
Open the calculator →Individual dish costings are valuable, but the real power comes from building a system that keeps all your costings current as ingredient prices change. Here is a practical approach for independent operators without dedicated finance staff.
Maintain a single reference document with all your ingredients, their package sizes, and current prices. Update this whenever you receive a supplier invoice with a price change. This becomes your single source of truth — when a price changes, you update it once and all affected dish costings are immediately recalculated.
Every dish on your menu should have a written standardised recipe specifying exact quantities for every ingredient, including garnishes and sauces. Undocumented recipes are impossible to cost accurately and lead to portion inconsistency across shifts and between staff members.
Block out two to three hours every quarter to update your ingredient prices and recalculate your top 15–20 dishes by sales volume. Flag any dish where the food cost percentage has moved more than 2–3 points since you last set the price. These are your candidates for repricing or reformulation.
Yield percentage is the proportion of a purchased ingredient that is usable after preparation. Here are typical yield percentages for common kitchen ingredients:
| Ingredient | Typical Yield % | Notes |
|---|---|---|
| Chicken breast (skinless) | 83–88% | After trimming fat and sinew |
| Beef fillet | 75–80% | After trimming chain and fat |
| Whole salmon (portioned) | 55–60% | After filleting and pin-boning |
| Salmon fillet | 88–92% | After portioning and trim |
| Onions | 88–90% | After peeling and root removal |
| Carrots | 82–85% | After peeling and tops |
| Broccoli | 70–75% | After removing stalk and outer leaves |
| Potatoes | 80–85% | After peeling |
| Fresh herbs (picked) | 60–70% | After picking leaves from stems |
These are averages. Weigh your trim for key proteins at least once and use your actual yield percentage rather than a standard table — it will be more accurate for your specific products and prep team.
Beyond prep yield, many ingredients lose significant weight during cooking. For proteins in particular, this cooking loss means your cost per gram of finished product is higher than your cost per gram of raw ingredient:
Both prep yield and cooking loss apply to the same ingredient. If you need 180g of cooked chicken breast and it loses 22% during cooking, you need to start with approximately 231g of raw (trimmed) chicken — before accounting for the prep yield loss from the raw purchased weight.
For recipe costing purposes, use the ex-VAT price you pay your supplier. Most raw food ingredients are zero-rated for VAT in the UK. Where VAT is applicable on certain processed items, use the net cost. Your selling prices will need to include VAT where applicable (20% for eat-in restaurant meals).
Calculate the total ingredient cost for the batch, divide by the number of portions it yields, and add the per-portion cost to each dish that uses it. For example, if a demi-glace batch costs £12 in ingredients and yields 30 portions, add £0.40 to every dish that includes a portion of that sauce.
Update whenever a key ingredient changes in price by more than 10%, and do a full review of all dishes at least quarterly. High-volume dishes warrant more frequent review because even small cost changes have significant cumulative impact at scale.
The most common and costly mistake is not accounting for prep yield when calculating ingredient costs. Using the edible portion weight rather than the as-purchased weight systematically understates your food cost, often by 10–20% for meat and fish dishes. This leads to menu prices that appear profitable on paper but generate lower actual margins once real kitchen losses are factored in.