Cooking & Nutrition Calculators

About these tools

Cooking is full of small calculations: a recipe serves four but you're feeding six, an old family card says "a cup of flour" and your new recipe is in grams, a British cookbook asks for gas mark 5, or you want to know what a bowl of homemade chili adds to your day. These four tools handle that arithmetic exactly and explain where every figure comes from, so you can check it yourself.

Exact math, honest about estimates

Some kitchen conversions are exact by definition. NIST defines the U.S. fluid ounce as 29.5735295625 mL, so cups, tablespoons and teaspoons convert to milliliters with no uncertainty at all, and the ounce and pound are fixed numbers of grams. The Fahrenheit-to-Celsius formula is exact too. Other figures are good estimates: how much a cup of flour weighs depends on how it was filled, gas marks are dial settings rather than precise temperatures, and calories in food vary between batches and brands. Each page tells you which kind of number you're looking at.

Where the data comes from

Ingredient densities and calorie values come from USDA FoodData Central, the U.S. government's reference food composition database, with each food's ID number listed so you can look it up. Baking weights for ingredients like flour and brown sugar come from the King Arthur Baking ingredient weight chart, which reflects test-kitchen weighing. Oven equivalents follow published tables from BBC Good Food and Which?, and the convection rule comes from King Arthur Baking. Label-style calorie rounding follows FDA nutrition labeling regulations (21 CFR 101.9).

A kitchen scale helps every tool

The single biggest improvement most home cooks can make to accuracy is weighing ingredients. Weight doesn't depend on how tightly an ingredient is packed, it makes scaled recipes more reliable, and it makes calorie counts for homemade food far more trustworthy. A basic digital scale that reads in 1-gram steps is enough for almost everything.

Cooking safely

Oven settings tell you how hot the air is, not whether food is cooked through. Use a food thermometer and the USDA Food Safety and Inspection Service's safe minimum internal temperatures — for example 165°F (74°C) for poultry — especially when you change batch sizes or pan sizes, which can change cooking times.

Connecting cooking to your goals

If you're tracking intake, pair the Recipe Calories per Serving Calculator with the Calorie Calculator or Macro Calculator in the Weight & Calories section. Remember that calories are one part of a healthy eating pattern; the Dietary Guidelines for Americans focus on the overall mix of foods over time.

The calculators in detail

Recipe Scaler

Multiplies every ingredient by servings wanted ÷ original servings and rounds the result to eighths or thirds, with the exact decimal alongside. It reads whole numbers, fractions, mixed numbers and ranges, and leaves lines like "salt to taste" for you to judge. The page includes a pan-area table so a scaled batter keeps the same depth.

Cooking Measurement Converter

Converts between cups, tablespoons, teaspoons, fluid ounces, milliliters, grams, ounces and pounds. Volume-to-volume and weight-to-weight conversions are exact by NIST definition; volume-to-weight uses a grams-per-cup density for the ingredient you choose, from USDA FoodData Central or the King Arthur Baking ingredient weight chart.

Oven Temperature Converter

Converts Fahrenheit, Celsius and gas mark using the exact temperature formula and the standard gas mark scale (gas 1 = 275°F, rising 25°F per mark). It also shows the fan or convection equivalent using published rules of thumb: about 25°F lower (King Arthur Baking) or 20°C lower (BBC Good Food).

Recipe Calories per Serving Calculator

Adds up the calories in up to eight ingredients — chosen from a list of 20 staples with USDA FoodData Central values, or entered from a package label — and divides by servings. It shows the exact figure and the rounded number an FDA-style nutrition label would print.