Ideal vs. Actual Food Cost: Where the Variance Actually Hides

August 10, 2026 · 3 min read

Multiply each dish's current plate cost by the units your POS says you sold, total it, and compare that against the COGS your inventory count produced. A week at $11,180 theoretical against $12,690 actual on $41,400 of sales is a 3.7-point gap. Recost first, or you are measuring stale recipes.

Computing the ideal

Theoretical (ideal) food cost

Σ (plate cost of each item × units sold that period)

Unit counts come from your POS product mix report. Plate costs come from your recipes — which is why stale recipes make this whole exercise meaningless.

Worked example · One week, four dishes

Burger — 220 sold × $4.20: $924
Salad — 140 sold × $2.10: $294
Salmon — 95 sold × $8.29: $788
Pasta — 180 sold × $2.90: $522
Theoretical food cost: $2,528
Food sales for these items: $11,295
Ideal food cost: 22.4%

Comparing it against actual

Worked example · The whole week

Theoretical food cost (all items): $11,180
Actual COGS from inventory: $12,690
Food sales: $41,400
Ideal food cost %: 27.0%
Actual food cost %: 30.7%
Variance in dollars: $1,510
Variance: 3.7 percentage points

Annualised, $78,520. None of it appears on any invoice. Those four inputs are all the variance calculator needs if you'd rather not do the annualising yourself.

The six causes, in the order that usually pays

#	Cause	The tell	First move
1	Stale recipe costs	Variance appears everywhere at once, evenly spread	Recost the top 20 dishes against current invoices
2	Over-portioning	Variance concentrated in one or two high-volume dishes	Weigh 20 random plates of your top seller
3	Comps, voids, staff meals	Variance tracks headcount or specific shifts	Pull the comp report by employee and reason
4	Spoilage	Concentrated in produce and dairy	Two-week waste log; then check par levels
5	Receiving errors	Variance spikes the week of a specific delivery	Reconcile invoices against what was actually put away
6	Theft	Persistent, dish-independent, survives every other fix	Investigate last — after the five above are ruled out

Why portioning is usually the answer

Because the arithmetic is brutal and invisible. Half an ounce of extra protein on a dish selling 200 a week, at $9.40/lb, is $0.29 a plate.

Worked example · The half-ounce problem

Spec: 6.0 oz
Actual average across 20 weighed plates: 6.5 oz
Extra cost per plate: $0.29
Plates per week: 200
Annual cost: $3,016

On one dish. Multiply across a menu and the whole variance is often explained without anyone having done anything wrong on purpose.

Why theft goes last

Not because it doesn't happen — it does. But it's a minority of variance in most kitchens, and an investigation that starts there costs you a team's trust before you've ruled out the five more likely explanations. Rule those out first and, if the variance survives, you'll be investigating from a much stronger position.

What a healthy variance looks like

0–1 point — normal operating friction. Monitor, don't chase.
1–2 points — worth a look at portioning and waste, no crisis.
3+ points — a system problem. Worth a dedicated week.
Negative — a data error, not a win. Usually a recipe cost that's too high or an over-counted closing inventory.

How do I get theoretical food cost without software?

Export your POS product mix to a spreadsheet, put your plate cost next to each item, and multiply. It's genuinely doable monthly for a menu of thirty items. It stops being doable weekly, which is the frequency that actually catches problems.

Do I need to count inventory every week?

For a real variance number, yes. Count what's expensive and what moves fast — proteins, seafood, dairy, alcohol. Most kitchens get most of the accuracy from about 20% of the SKUs, which makes a 45-minute weekly count realistic.

What if my POS doesn't do product mix?

Almost all do, though it may be called a PLU report, item sales report or menu mix. If yours genuinely doesn't, ring-level sales data plus menu prices will get you unit counts.

Theoretical vs. actual, without the spreadsheet.

Marji keeps every recipe costed against your current invoices, so your theoretical number is right on the day you look at it — and the dishes that drifted are named, not hunted.

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