Recipe Scaler / Serving Size Calculator
Enter the number of servings the recipe was written for, the number you actually want to make, and your ingredient list, and this calculator finds the scaling factor and multiplies every quantity by it. It keeps unrounded math internally and rounds each result to two decimals, so a recipe for four that you want to stretch to six comes out cleanly. Linear scaling is exactly right for most ingredients, but a few — pans, cooking time, leavening, and strong spices — need a cook's judgment rather than a straight multiply.
Servings
Ingredients
Scaling factor
×1.5
6 ÷ 4 servings
Scaled ingredients
Original vs scaled amounts
How it works
The scaling factor is simply your desired servings divided by the original servings. A recipe written for 4 that you want to make for 6 has a factor of 6 ÷ 4 = 1.5, and a recipe for 4 you want to halve to 2 has a factor of 0.5. This single ratio is what every ingredient gets multiplied by, so the proportions between ingredients never change — only the batch size does.
Each ingredient's new quantity is its original amount times the factor: 2 cups of flour at a 1.5× factor becomes 3 cups, and 1 teaspoon of salt becomes 1.5 teaspoons. The tool multiplies with the full unbroken factor and only rounds the final number to two decimals, so repeated fractions like 1/3 cup scale without the drift you get from rounding partway through. Units are carried through unchanged — it scales the number, not the measure.
The result table lists every ingredient side by side, original next to scaled, and the optional chart shows the before-and-after amounts for ingredients you entered as numbers. Because scaling is purely proportional, doubling the servings doubles every quantity and the ratios among them stay identical — which is why the same factor works whether you are cooking for two or for twenty.
Frequently asked questions
Does scaling a recipe by this factor always work?+
For the bulk of a recipe — flour, sugar, liquids, produce, proteins — straight proportional scaling is exactly what you want, and that is what this calculator does. Where it breaks down is with things that do not respond linearly to batch size: salt and strong spices often need less than the math suggests when you scale up (and can taste flat when you scale down), and rich flavors like garlic or chili can overwhelm a doubled batch. Treat the scaled spice amounts as a starting point and taste as you go.
Why doesn't the tool adjust pan size, oven temperature, or cook time?+
Because those do not scale with a simple multiply. Doubling a batter does not mean doubling the bake time or the pan area — a deeper pan changes how heat reaches the center, so time usually grows far less than the volume does, and temperature often stays the same or drops slightly. Leavening (baking soda, baking powder, yeast) is especially touchy: it interacts with pan geometry and rise time, so a straight 2× can over- or under-inflate a bake. Use a pan-conversion calculator for the vessel and rely on doneness cues, not the clock, when you change batch size.
How precise are the scaled quantities?+
The numbers are mathematically exact to two decimal places, computed from the unrounded factor so there is no rounding drift. In a real kitchen, though, you will round to what your measuring tools can actually do — you cannot scoop 0.67 of a teaspoon precisely, so you would round to the nearest common fraction. This is a general cooking aid, not a substitute for a tested recipe: for baking especially, weighing ingredients in grams gives far more reliable results than scaling volume measures.