About Kitchen Calculator
I'm Eric Stermer. I'm a software developer, and I built Kitchen Calculator for myself. I cook breakfast most days and I meal-prep on Sundays for the week ahead. Somewhere in the middle of doing both, I got tired of pulling my phone out with floury hands to look up how many grams are in a cup of honey, whether 350°F is gas mark 4, or what happens to a cake when you bake it in a 9-inch square instead of a 9-inch round. So I sat down and built the small set of calculators I kept wanting, and I put them on a public site so anyone else with the same questions could use them too.
What the tools do
There are five tools. Recipe Rescaler scales any recipe by a multiplier, with an option to fix leaveners and salt instead of scaling them linearly. Cups to Grams converts US volume measurements to weight using an ingredient density table. Substitution Finder suggests ingredient swaps from a short, tested list. Pan Size Converter scales a recipe between pans of different shapes and sizes by comparing the area of the original pan to the area of the new one. Oven Temperature converts between Fahrenheit, Celsius, and UK gas marks, with a separate adjustment for convection ovens.
Each tool does one thing and is built to be used mid-cook: short page, big inputs, fast answer, no signup.
How the numbers are put together
The cup-to-gram table covers roughly 60 common baking and cooking ingredients. The values come from published ingredient density references, USDA nutritional data, and standard professional baking sources. Where density varies meaningfully by form (e.g., sifted vs. spooned flour, packed vs. loose brown sugar), the table uses the form most recipes mean when they say "1 cup." If you're weighing for baking where precision matters, a kitchen scale is still a better answer than any table.
Pan conversion uses the ratio of pan areas. The math assumes batter depth stays the same, which is the usual assumption when scaling between similar pans. Bake time is a rule of thumb, not a guarantee — every oven runs a little different, and the right way to check doneness is with a toothpick, an instant-read thermometer, or whatever test the recipe specifies.
Substitutions are kept short on purpose. Long substitution lists produce risky results; a focused list of well-tested swaps produces reliable ones. If a swap isn't on the list, that's intentional.
Oven temperatures use the standard UK gas-mark scale. Convection adjustment defaults to 25°F (about 15°C), which is the common rule of thumb; you can override it if you know your oven.
Why meal prep matters here
Sunday meal prep for the week is when most of these tools actually came together for me. Cooking for one person and cooking for five are not the same recipe at different scales. Doubling a recipe by hand almost always breaks something — leavening, salt, cook time. Cooking for the week also means changing pans: the recipe that fits an 8-inch round for Saturday brunch needs a 9×13 for Sunday meal prep. The pan-area math and the leavener-handling on the recipe rescaler exist because of that weekly jump, not in the abstract.
Updates
The data tables — densities, pan sizes, gas marks — get checked and updated periodically. If something looks off, or if you have a correction or a tool request, the contact page is the easiest way to reach me. I read everything that comes in.
Disclaimer
Results are estimates for everyday cooking, not a substitute for a tested recipe or professional advice. Baking is chemistry and small differences matter — when precision matters, weigh your ingredients, calibrate your oven, and follow a recipe you trust. Food-safety guidance always applies when handling raw eggs, flour, dairy, or perishables.