Recipe Rescaler

How it works

Each line is parsed into a quantity, unit, and ingredient. Volume units (cups, tablespoons, teaspoons, milliliters, ounces) are converted to grams using per-ingredient density, multiplied by your scale factor, then converted back to the requested unit. Whole units (eggs, cans) and gram-only ingredients are multiplied directly and rounded to kitchen-friendly quarters.

Leavening agents — baking powder, baking soda, yeast, and sourdough starter — follow a separate, gentler growth curve so the chemistry still works at 2x, 3x, or 4x. Eggs scale to whole numbers and flag fractional results, since a half egg in a recipe usually means beat one egg and measure half of it.

Worked example

Scaling a 9-inch cake recipe to a 12-inch cake (about 1.78x). Two cups of flour becomes 3.5 cups (rounded down from 3.56 to a usable quarter). One teaspoon of baking powder at 1.78x is held to about 1.25 teaspoons rather than the literal 1.78, because doubling leavening by 1.78x would overshoot the lift. Two large eggs at 1.78x round to 4 whole eggs with a note explaining the partial egg math if you ever want it back.

Common mistakes

Don't scale bake time with ingredient volume — a doubled recipe in the same pan takes roughly 20% longer, not 100%. Don't apply this tool's leavening curve to ingredient swaps (use the substitution tool for that). Don't enter percentages or vague amounts like "a pinch" or "to taste" — the parser ignores lines it can't read and scales only what it understood.

FAQ

Why are fractions rounded to quarters? Because 1/4 cup, 1/2 teaspoon, and 3/4 tablespoon are the smallest units most kitchen measuring spoons and cups actually carry. Smarter math loses to the limits of the tools you measure with.

Can I scale down? Yes — factors below 1.0 work the same way. For very small batches (under 0.5x), gram weights often give a more reliable result than cup measures.

What about spices, salt, and vanilla? They scale linearly with the rest of the recipe. Most baking texts treat salt as non-leavening, so it follows the standard factor rather than the leavening curve.