How we calculate cost per serving
Every price on SeasonSort traces back to a public USDA report, and every per-serving number is arithmetic we do ourselves. This page explains exactly how — including the parts that are precise, the parts that are estimates, and the places we can be wrong. If you're going to trust a number, you should know how it was made.
Where the prices come from
Produce prices come from the USDA National Retail Report – Specialty Crops, published weekly by the USDA's Agricultural Marketing Service. Meat, poultry, and egg prices come from the matching weekly retail reports for beef, pork, chicken, turkey, and eggs.
These reports aggregate advertised supermarket prices from hundreds of retailers across roughly 29,000 stores, broken out by US region. We cover 6 regions. The USDA publishes on Fridays; an automated job pulls the new report every Saturday, so what you see is this week's ads.
How we turn a report into one price
A single commodity might appear in a report many times — different varieties, package sizes, organic and conventional. We narrow it down in three steps:
- Filter to conventional and to the variety and pack size we track for that item (for example, sweet corn priced each, not in a 4–5 ear tray).
- Weight by reach. Each advertised price is weighted by the number of stores running that ad, so a price promoted in 900 stores counts more than one in 12. The result is a store-weighted average, not a simple mean.
- Compare to last week to produce the week-over-week change you see next to each item.
From price to "per serving"
Prices arrive in whatever unit the store advertised — per pound, each, per pint. To make items comparable we convert to a serving:
serving cost = price ÷ (grams per price unit) × (grams per serving)
Each tracked item carries a typical serving weight (a 150 g peach, a 113 g portion of ground beef). Calories and protein use the same weights, scaled from per-100g values in the USDA's FoodData Central database. Those are our own calculations, not numbers copied from another site.
How a recipe gets a cost
Recipe cost is where estimation enters. For each ingredient line we:
- Parse the quantity and unit — including fractions like 1½ cups and ranges like 3.5–4 lbs.
- Match the ingredient to something we price: this week's produce, this week's meat, or a maintained table of pantry staples (flour, oil, rice, spices).
- Convert the amount into the item's price unit and multiply.
Add the lines together, divide by the recipe's yield, and that's cost per serving. Change your region and every recipe re-prices, because the produce and meat underneath it re-price.
What's exact and what isn't
This is the important part.
- Produce and meat prices are exact for the week and region shown — they're the USDA's weighted averages, not our guesses.
- Recipe costs are estimates. When a recipe contains an ingredient we can't confidently price, we fall back to a small flat estimate for that line and mark the whole recipe with a ~ before the price. A tilde means "close, not exact."
- Nutrition on recipe pages is the source blog's published value when they publish one; our computed value otherwise.
Where we can be wrong
Honest limitations, in rough order of how much they matter:
- These are advertised prices, not shelf prices. The USDA report captures what's promoted. A store's everyday price for an item nobody advertised won't appear, and your local store may not run the ad at all. Treat the numbers as a strong regional signal, not a receipt.
- Ingredient matching is best-effort. "Crushed red pepper" is not a bell pepper and "corn starch" is not sweet corn; we exclude cases like those explicitly, but free-text ingredients from thousands of recipes will never match perfectly.
- Pantry staples are reference costs from a maintained table, not live data. They move slowly, but they're not this week's price.
- Serving weights are typical, not yours. Your "one peach" may not be 150 g.
- Regions are broad. "Midwest" covers a lot of ground.
How often it changes
Weekly. The USDA publishes Fridays; we refresh Saturdays. Prices, the week-over-week deltas, the "cheapest to cook right now" ranking, and every recipe cost all move together when the new report lands.
If a number ever looks wrong to you, it might be — tell us and we'll dig into it.
Questions or a correction? Get in touch. More on our data sources in About.