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Portion Drift Cost Calculator

Reviewed for 2026, updated September 8, 2026.

Estimates how much over-portioning a single ingredient costs per plate and per year, and how many food cost points it adds, for kitchens trying to hold plate consistency.

Your numbers

Results update as you type.

Your estimate

Ingredient cost per plate at spec...
Extra cost per plate from drift...
Annual cost of portion drift...
Food cost points added on this item...

Estimates only. Assumptions are listed below, and you can change every input.

A protein spec of 6 ounces that goes out at 6.75 ounces looks harmless on any single plate. Multiplied across every cover, every week, it becomes one of the largest invisible line items in a kitchen, and it never shows up on an invoice because you did buy the product. It shows up as a food cost percentage that drifts upward while the menu, the prices and the recipes all stay exactly the same.

This estimator compares the cost of the spec portion against the cost of the portion actually being served, using your purchase price per pound. The difference is the drift cost per plate. That figure is multiplied by plates per week and weeks open per year to give the annual cost, and divided by the menu price to show how many percentage points of food cost the drift is adding on that item. It covers one ingredient at a time, so run it separately for each high-cost component you want to check.

How to use this tool

  1. Weigh a sample of plated portions across different cooks and shifts and enter the average actual weight next to the spec weight from the recipe card.
  2. Enter the price per pound you currently pay for that ingredient, the number of plates of the item you sell in a typical week and how many weeks a year you are open.
  3. Add the menu price to see how many food cost percentage points the drift is adding, then use the annual figure to decide whether scales, portion tools or retraining are worth it.

What the math assumes

  • One pound equals 16 ounces, and the ingredient price per pound is the as-purchased price you pay.
  • Only the single ingredient you enter drifts; sides, garnish and other components are assumed to stay on spec.
  • The average actual portion you enter is representative of every plate served, so weigh a sample across shifts to get a fair number.
  • Annual cost is drift per plate multiplied by plates per week and weeks open, with no seasonality adjustment.
  • A negative result means plates are going out under spec, which saves money on paper but is a consistency and guest satisfaction problem, not a win.

Frequently asked questions

How many plates should I weigh to get a fair average portion?

Enough to cover different cooks and both busy and slow periods. A dozen plates from one quiet lunch will not tell you much; spreading the sample across a full week gives a more honest average.

Can I use this for items sold by count or by volume instead of weight?

The tool is built for portions weighed in ounces with a price per pound, so it divides the price by 16 to get a cost per ounce. You can still use it for count or volume items as long as the units stay consistent: enter the spec and actual amounts in the same unit, and in the price field enter what 16 of that unit costs you, for example the cost of 16 pieces or 16 fluid ounces. The math then works the same way.

What about ingredients that lose weight in cooking?

Decide whether your spec is a raw weight or a cooked weight and weigh the actual portion at the same stage. Mixing raw specs with cooked weights will make the drift look larger or smaller than it really is.

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