Recipe Scale Conversion Calculator

One factor, every ingredient

Scaling a recipe is one multiplication applied to every ingredient. Divide the servings you want by the servings the recipe makes, and that number is your scale factor. A recipe written for 4 that needs to feed 10 uses a factor of 10 / 4 = 2.5, and every cup, tablespoon, ounce and gram in the ingredient list gets multiplied by 2.5. Going the other way, cooking a 6 serving pot of chili for 2 people uses a factor of 2 / 6 = 0.33, so every ingredient shrinks to a third.

This works without surprises for what cooks call linear ingredients: flour, sugar, rice, stock, oil, butter, meat, vegetables. Double the factor, double the flour. The calculator on this page applies the factor for you and reports it, so you can sanity check any ingredient by hand. What it also reports is a second, smaller factor for salt and dried spices, because those two refuse to follow the same straight line, and a note on baking time, which follows pan geometry rather than serving counts.

Worked example: 4 servings up to 10

Take a soup written for 4 that contains 2 cups of broth, 1 cup of diced tomatoes, 1 teaspoon of dried oregano and 0.5 teaspoons of salt, and scale it to 10 servings. The factor is 10 / 4 = 2.5.

• Broth: 2 cups x 2.5 = 5 cups
• Tomatoes: 1 cup x 2.5 = 2.5 cups
• Meat or vegetables: every ounce x 2.5
• Oregano: 1 + (2.5 - 1) x 0.5 = 1.75 times the original, so 1.75 teaspoons
• Salt: 0.5 x 1.75 = 0.875 teaspoons, in practice a rounded 0.75 to 1 teaspoon

The seasoning line is the one people get wrong by instinct, and usually in the direction of too much. Full factor salt in a soup you taste at the end tends to land salty, because you cannot taste the pot until it is done. The safer workflow for any scaled batch: add the reduced spice amount, simmer, taste, then adjust upward. You can always add salt, but the only fix for an over salted 10 serving pot is making more of everything else.

Salt and spices are not linear

Seasoning follows a curve, not a line, for a plain reason: salt and spice are about the surface of the food and the taste buds eating it, and neither grows as fast as volume. A doubled pot does not need doubled salt to taste equally seasoned. The kitchen rule of thumb that works across most Western and home cooking is to add half of the increase beyond a doubling:

Fresh herbs, garlic and citrus zest sit somewhere in between; many cooks scale them at about three quarters of the increase. These are starting points, not laws, and taste is the final tool. But as a first guess the half rule prevents the two classic scaled batch disasters: a chili that burns on the way down, and a soup that tastes like the sea.

Baking time does not scale with the factor

Here is the counterintuitive part that ruins scaled baked goods. Baking time depends on how deep the batter or dough sits in the pan, not on how much of it there is. Double the recipe and split it into two pans of the original size, and the time barely moves. Double the recipe into one deeper pan, and the center is still raw when the edges overbake, because heat travels from the outside in at roughly the same speed every time.

The practical rules:

• Same depth in the pan: keep the original time, check a few minutes early
• Deeper by about 1 inch: add roughly 10% to 20% more time
• Deeper by 2 inches or more: add 25% to 50%, lower the oven 25 degrees F, and test the center
• Shallower, as in scaling down: start checking 10% early

Test doneness with a thermometer or a toothpick rather than the timer on a scaled batch. Cake is done near 200 to 210 degrees F internal, quick breads around 200, and custards firm up well before they look done. A scaled batch is exactly the wrong place to trust the clock, because the original time was tuned to the original depth.

Pan size and batch geometry

Because depth drives baking time, pan area is the number to compare when scaling. Multiply length by width for each pan and match areas:

So a standard brownie recipe in an 8 by 8 doubles into a 9 by 13 almost perfectly: 64 x 2 = 128 square inches wanted, 117 available, close enough that the batch bakes slightly thicker and needs a few extra minutes. Tripling an 8 by 8 will not fit any single standard pan without changing depth, so use two pans or plan the longer bake. Loaf pans, Bundt pans and springforms carry their volumes on the bottom, and matching volume, not area, is what matters for those shapes.

Leaveners, eggs and thickener edge cases

A few ingredients break the simple rules and deserve their own handling:

• Baking powder and baking soda. Treat them like spices: half of the increase beyond doubling, or the metallic taste of excess leavener shows up in the crumb. For a factor of 2.5, use 1.75 times the original.
• Eggs. You cannot buy 0.4 of an egg. One large egg is about 3 tablespoons of beaten egg, so for a factor of 1.5 use 1 egg plus 1.5 tablespoons. For a factor of 2.5 use 2 eggs plus 1.5 tablespoons.
• Yeast. Roughly linear up to a tripling, but big batches rise faster than small ones because the mass holds its own heat, so watch the dough, not the schedule.
• Flour as thickener. In sauces and gravies, flour and cornstarch scale with the liquid, so use the full factor there.
• Alcohol in braises. Scale below the factor, around 1.5 times at a doubling, or the batch tastes boozy before the liquid cooks down.

Water, stock, oil, sugar and dry goods for baking follow the plain factor with no drama. It is the biological and chemical actors, eggs, yeast, salt, leaveners, that demand the modified numbers.

Weight beats volume when scaling

Volume measurement carries hidden error even in an unscaled recipe. A cup of scooped flour can weigh anywhere from about 120 to 150 grams depending on how hard you scoop, a spread of 25%. In the original recipe that error hides. Multiply the recipe by 2.5 and a 25% error becomes a quarter cup of flour you never planned for, and scaled doughs and batters are less forgiving of it.

The fix costs nothing: weigh in grams. Grams multiply cleanly, 480 grams of flour at a factor of 2.5 is 1,200 grams, no measuring cups involved. A kitchen scale that reads to 1 gram costs about the same as a single bag of flour and removes the whole problem. If a recipe lists both cups and grams, trust the grams when scaling; if it lists only cups, converting the staples once is worth ten minutes. The USDA safe temperature chart and the USDA food safety guidance both stay constant regardless of batch size, so the one number that never scales is the internal temperature your finished dish has to reach.