Methodology

Every number on RationMath comes from two inputs: a product's total calories and its price. Here's exactly how we get them and what we do with them.

The formulas

• Cost per 2,000 calories = price ÷ total calories × 2,000
• Days of food (1 person) = total calories ÷ 2,000
• Calories per day as sold = total calories ÷ the number of days the brand advertises
• Calculator: calories needed = people × days × calories per day. For each product, the number of units = calories needed ÷ product calories, rounded up.

We use 2,000 calories as one person-day because it's a common planning figure for an adult. It isn't a recommendation for any individual.

Where calorie data comes from

We read each product's page on the brand's own website and record the source link and the date we checked it. Each product gets one of three labels:

• Label total The brand states a total calorie figure for the kit (23 products).
• Brand per-day claim The brand states calories per day and a number of days, and we multiply them (11 products). This trusts the brand's per-day figure, so we treat it as weaker. We plan to confirm these by adding up the calories on each item's nutrition panel.
• Needs review We couldn't find a usable total (3 products). These are not ranked.

The rankings page has a filter that shows only products with a label total.

Where prices come from

Right now, prices are the list price on each brand's store on the date shown, entered by hand. Sales are common and prices change, so always check the seller's page. We plan to move to daily price updates from retailer product feeds, and to show price history on each product page.

Shipping isn't included, because it depends on where you live.

What we don't measure

• Taste, texture or quality. We haven't eaten these products.
• Nutrition beyond calories, such as protein, vitamins, sodium or allergens.
• Water needed for preparation, shelf life claims, packaging quality or customer service.

Cost per calorie is a way to compare how much food you get for your money. It isn't a verdict on which food is best for you.

Corrections

Brands change products and labels. If a number here doesn't match the current label, the label wins, and we'll correct the data.

Independence

Rankings are sorted purely by the formulas above. No brand pays to be listed or to rank higher. See our affiliate disclosure.