Recipe Scaler & Pan Size Converter
Turn any recipe into half-batches or party size
Recipe scaling, pan swapping and fractions FAQ
What is the easiest way to scale a recipe?
For most home cooking, the easiest method is to scale by servings. Decide how many servings the original recipe makes, decide how many you need now, and let the calculator find the factor and multiply the amounts for you. If the original serves 4 and you need 10, the factor is 10 ÷ 4 = 2.5, so every amount is multiplied by 2.5.
When should I use pan size mode instead?
Pan size mode is especially helpful for cakes, brownies and bar cookies. Those recipes care about the depth of the batter in the pan. Here the tool uses pan area ratios to suggest how much to scale the batter when moving between common pans (for example 8" round to 9" round or 8" square to 9"×13"). You still need to keep an eye on bake time and doneness.
Why do my scaled amounts sometimes use fractions?
Many home recipes are written in cups and spoons, which feel friendlier as fractions like 1/3, 1/2 or 3/4. The “Friendly fractions” option converts scaled decimals into the nearest eighth of a unit. So 0.66 becomes about 2/3, and 1.75 becomes 1 3/4. If you prefer to plug numbers into a scale, switch to “Decimals” instead.
Can I use this for metric recipes in grams and millilitres?
Yes. The scaler just multiplies the quantities; a line that starts with “250 g flour” will be treated just like “2 cups flour”. For precise baking, it is often best to start from a metric recipe and leave the number style on decimals so you can weigh ingredients accurately in grams.
Does this change cooking or baking times automatically?
No. The tool focuses on ingredient amounts. Scaled recipes, especially baked goods and large roasts, often need new cook times and temperature tweaks. Use the scaled amounts as a guide, then rely on doneness tests (skewer tests, visual cues, food thermometers) and trusted recipes for timing.
Is there any limit to how far I can scale?
The maths works for almost any factor, but the kitchen reality does not. Very large batches can brown differently, reduce more slowly and change texture. Very tiny batches may be hard to stir or spread evenly. As a rough rule, factors between 0.5× and 3× are usually easier to manage than extreme scaling.
How does the tool handle ranges like “2–3 cloves”?
If a line starts with a clear range (for example “2–3 cloves garlic”), the scaler multiplies both ends and keeps it as a range (for example “3–5 cloves garlic” at roughly ×1.5). For loose seasonings like salt and pepper, you can also just eyeball amounts to taste after scaling.
Will this keep baker’s percentages consistent?
Yes. When a dough or batter is written with ingredients in fixed ratios, multiplying every ingredient by the same factor keeps those ratios identical. If you know the original hydration and fat percentage, the scaled dough or batter will share them, as long as you scale all ingredients and not just the flour or main component.
How to use this recipe scaler and pan size converter
This tool is designed to take the boring maths out of scaling recipes. Instead of juggling fractions in your head, you tell it how you want a recipe to change, paste the ingredient list, and copy the updated version into your notes or document.
1. Pick the scaling mode that fits the job
For stews, pasta bakes, stir-fries and day-to-day recipes, choose “By servings”. Enter how many servings the recipe makes now and how many you want. For cakes and brownies, pick “By pan size” and select a pan swap like 8" round to 9" round. When you already know your factor (for example you want a 2.5× batch to stock the freezer), use “By factor only”.
2. Set number style: fractions or decimals
Next, choose how the scaled amounts should look. Friendly fractions are ideal when your measuring tools are cups and spoons. The scaler rounds to the nearest eighth, so you see things like “1 1/4” and “2 2/3” instead of awkward decimals. If you like measuring on a scale, leave the setting on Decimals for clean numbers you can weigh in grams or millilitres.
3. Enter servings or confirm the pan swap
In servings mode, fill in original servings and new servings. The tool calculates the scale factor from those two numbers. In pan mode, the factor is based on the surface area ratio of the pans you choose, so your batter depth stays in the same ballpark. For factor mode, just type the factor directly (e.g., 0.5 for a half batch, 3 for triple).
4. Paste ingredients with amounts first
Paste your ingredient list into the box, one ingredient per line. The scaler looks for a number at the start of each line, including common patterns such as “1 1/2 cups flour”, “3/4 tsp salt”, “250 g sugar” or even simple ranges like “2–3 cloves garlic”. It multiplies those numbers by the scale factor and leaves the rest of each line alone.
5. Copy the scaled list into your recipe
When you hit Scale this recipe, the result card shows the factor, how it was calculated, and a fresh ingredient list under “Scaled ingredients”. Use the Copy summary button to drop everything into a note, email or document. From there you can tweak wording, add method notes and adjust cooking times.
Used this way, the scaler becomes a small kitchen assistant: it keeps the maths tidy, helps you move between pans or servings without wrecking ratios, and lets you stay focused on flavour and timing instead of fractions.
How the recipe scaling and pan math works
Under the hood, this tool uses simple, transparent maths. The goal is not to be clever—it is to be predictable, so you can sanity-check numbers with a calculator or a scrap of paper if you want to.
1. Finding the scale factor
In servings mode, the scale factor is:
factor = new_servings ÷ original_servings
If a soup serves 4 and you want 10 servings, factor = 10 ÷ 4 = 2.5. Every amount is multiplied by 2.5. In factor mode you simply supply this number directly. In pan mode, the factor comes from pan area.
2. Pan area ratios for common cake and brownie pans
For each supported pan, the calculator stores an approximate area in square inches. For example, an 8" round pan has an area of about π × 4², while a 9" round pan has π × 4.5². The scale factor for moving from pan A to pan B is:
factor = area_B ÷ area_A
This keeps batter depth similar as long as you are not making extreme changes. You still need to use a skewer test and your oven sense to adjust bake times.
3. Parsing amounts at the start of each line
For each ingredient line, the scaler looks from the start of the line until it hits a non-number character (other than spaces, decimal points or the fraction slash). It understands:
- Whole numbers (e.g., “2 eggs”).
- Fractions (e.g., “1/3 cup oil”).
- Mixed numbers (e.g., “1 1/2 cups flour”).
- Simple ranges such as “2–3” at the start of the line.
It converts that text into a decimal, multiplies by the factor, then formats the result back into fractions or decimals depending on the number style you chose.
4. Turning decimals into friendly fractions
When “Friendly fractions” is selected, scaled amounts are rounded to the nearest eighth:
fraction_part ≈ round(decimal_part × 8) ÷ 8
The tool then simplifies that fraction and combines it with any whole-number part. So 1.66 becomes roughly 1 2/3, and 0.125 becomes 1/8. If the fraction rounds up to a whole unit (for instance 0.99 of a cup), it is carried into the whole number.
5. Classifying the scaling plan
The green/amber/red flag is based on how aggressive the scale factor is:
- GREEN when the factor is roughly between 0.5× and 3×, a comfortable range for most home recipes.
- AMBER for moderate extremes (about 0.25×–0.5× or 3×–4×) where texture, browning and pan choice might need extra thought.
- RED for very small or very large factors, where you are usually better off doing two batches or designing a fresh recipe.
This is not a hard rule, just a nudge to think twice before turning a single cake into a giant bakery tray or trying to bake one cupcake from a whole-layer recipe.
Because the maths is simple and open, you can always tweak factors, re-run the scaler and fine-tune the rounded amounts until they feel right for your kitchen.
References and further reading on scaling recipes and pan sizes
Pair this recipe scaler with detailed guidance on scaling, weighing and pan conversions:
- King Arthur Baking — How to reduce a recipe — explains practical ways to scale recipes down, including working with baker’s percentages and ingredient weights.
- King Arthur Baking — Ingredient weight chart — a handy reference for converting between cups, ounces and grams for common baking ingredients.
- Serious Eats — How to scale a recipe for cake to fit any pan — in-depth discussion of pan areas, batter volumes and how to adjust cake recipes for different pans.
- USDA FSIS — Kitchen Companion: Your Safe Food Handbook — broad food safety handbook covering safe cooking temperatures, storage and handling for scaled-up meals.
Use the scaler for the numbers, and lean on trusted cookbooks, baking sites and food safety resources to tune pan choices, bake times and internal temperatures for your actual kitchen.