Recipe Scaler

Scaling a recipe up or down should be straightforward, but recalculating every ingredient by hand is tedious and error-prone. This recipe scaler lets you enter your original serving count, your target serving count, and all your ingredient quantities; it then outputs every adjusted amount in seconds.

How to Use the Recipe Scaler

1. Enter the original number of servings the recipe is written for.
2. Enter the number of servings you want to make.
3. Add each ingredient with its original quantity and unit (e.g., 250g flour, 2 eggs, 1 tsp salt).
4. Click Scale Recipe to see all adjusted quantities.
5. Print or copy the scaled ingredient list for use in the kitchen.

The Formula

New quantity = original quantity x (desired servings / original servings).

The ratio of desired servings to original servings is the scaling factor. If you want to double a recipe that serves 4 to serve 8, the scaling factor is 8/4 = 2.0, so every ingredient is multiplied by 2. To scale down a recipe that serves 12 to serve 3, the factor is 3/12 = 0.25, so every ingredient is multiplied by 0.25.

The same formula applies regardless of units: multiply grams, millilitres, cups, tablespoons, or whole items by the same factor.

Real-World Example

A chocolate cake recipe serves 8 and calls for: 200g plain flour, 150g caster sugar, 100g butter, 3 eggs, 50ml milk, 1 tsp baking powder.

You want to make it serve 12. Scaling factor = 12/8 = 1.5.

• Flour: 200 x 1.5 = 300g
• Sugar: 150 x 1.5 = 225g
• Butter: 100 x 1.5 = 150g
• Eggs: 3 x 1.5 = 4.5 (round to 4 or 5 eggs in practice)
• Milk: 50 x 1.5 = 75ml
• Baking powder: 1 x 1.5 = 1.5 tsp

Scaling Tips for Baking vs. Cooking

Scaling savoury cooking is generally forgiving. Soups, stews, and sauces scale linearly with little adjustment needed. Baking is less straightforward because scaling affects not just ingredient quantities but also cooking chemistry. Leavening agents (baking powder, baking soda, yeast) should be scaled conservatively; using the full calculated amount for large batches can result in over-leavened, collapsed baked goods. When doubling a bake, increase leavening by about 25% less than the full calculated amount. Spices and salt also benefit from starting at about 75% of the calculated amount and adjusting to taste.

Frequently Asked Questions

Do cooking times change when I scale a recipe? Cooking times do not scale linearly with serving size. If you double a batch of soup, the volume increases but a single pot still heats at roughly the same rate, so cooking time changes little. For baked goods in larger tins, increase the baking time slightly and test for doneness. Smaller portions cook faster, so check early.

How do I handle fractional egg quantities? Eggs are the trickiest ingredient to scale precisely. For small fractions (e.g., 0.5 an egg), beat the egg and measure half by volume, typically about 25ml per half egg. For recipes where one extra or fewer egg would significantly change the texture, adjust other liquids slightly to compensate.

Can I scale recipes that use cup measurements? Yes. The formula applies to any unit. The tool will multiply cup quantities by the scaling factor. You may end up with unusual fractions (e.g., 1.75 cups), which you can approximate with standard measuring cups or convert to millilitres for precision.

What is the best way to handle spice scaling? Scale spices at about 60-75% of the calculated amount for large batches, because strong flavours intensify as cooking reduces liquid. For scaling down (making fewer servings), the full calculated amount is usually fine. Taste and adjust at the end of cooking regardless of the scaling direction.

Scaling a bread dough from two loaves to five

Bread is the easiest thing to scale and the hardest to scale badly. The dough is weighed, the hydration is a percentage, and nothing depends on a chemical reaction with a narrow tolerance.

A basic white dough written for two loaves calls for 1,000 g of strong white flour, 650 g of water, 20 g of salt and 10 g of instant yeast.

You want five loaves. The scaling factor is 5 divided by 2, which is 2.5.

The linear result is the starting point, not the finish. Salt at 50 g in 2.5 kg of flour is 2 percent of the flour weight, which is the same percentage as the original and therefore the right figure for the dough. A baker reducing salt for a large batch would use 75 percent of the calculated amount, which is 37.5 g. That is a taste decision, not an arithmetic one.

Baker's percentage and the conversion factor

Baker's percentage expresses every ingredient as a percentage of the flour weight, with the flour always at 100 percent. King Arthur Baking describes the method that way in its reference page, and it is the standard notation in professional bakeries.

Read the original dough as percentages and it becomes portable.

The percentages add to 168, which means the dough weighs 168 percent of the flour weight. Two thousand four hundred grams of flour therefore yields 4,032 g of dough.

That total is what you need to size a batch. Five loaves at 800 g each is 4,000 g of dough. Dividing 4,000 by 1.68 gives 2,380.952381 g of flour, so 2,400 g is the practical rounding and it leaves about 32 g of spare dough.

The scaling factor between two formulas is called the conversion factor, and it is the target flour weight divided by the formula flour weight. From 1,000 g to 2,400 g the conversion factor is 2.4. Every ingredient in the formula multiplies by the same number, which is exactly what the recipe scaler does when it is handed a serving count instead of a flour weight.

The advantage of working this way is that hydration, salt and yeast stay fixed as percentages while the batch size moves. A dough at 65 percent hydration behaves the same at two loaves and at fifty.

Changing the tin without changing the depth

Serving counts are not the only thing you scale. A cake recipe written for one tin often has to fit another.

The controlling quantity is the volume the tin holds, and volume is the base area multiplied by the depth. Areas first.

Moving a recipe from a 20 cm round tin to a 23 cm round tin multiplies the base area by 1.322500. To fill the bigger tin to the same depth you scale the recipe by that factor, which is a rise of about a third.

Two comparisons in the table catch people out. The 22 cm round tin holds 1.21 times the 20 cm round, not 1.1 times, because area grows with the square of the diameter. And a 20 cm square tin holds 1.273240 times a 20 cm round tin, because the square uses the corners.

If you would rather not scale the recipe, keep it and accept a shallower cake. The same 1,570.796327 cubic centimetres of batter spread across the 23 cm tin is 3.78 cm deep instead of 5 cm, which shortens the baking time and changes the crust.

Spoons, and what to do with 3.75 teaspoons

Scaled quantities rarely land on whole spoons, and a kitchen has no measuring spoon for the number the calculator prints.

Two conversions cover most cases. A teaspoon is 5 millilitres and a tablespoon is 15 millilitres, so a tablespoon is three teaspoons.

Take a recipe with 2 teaspoons of baking powder scaled by 2.5. The linear answer is 5 teaspoons, which is 25 millilitres. Applied against the leavening guidance set out below, 25 percent comes off, leaving 3.75 teaspoons, which is 18.75 millilitres.

Phrased in kitchen measures, 3.75 teaspoons is one tablespoon plus three quarters of a teaspoon. That is measurable with two spoons and no arithmetic at the counter.

The same treatment works downwards. A quantity of 0.75 of a teaspoon is 3.75 millilitres, and a quarter teaspoon is 1.25 millilitres. Writing the millilitre figure next to the spoon figure on a printed recipe removes the guesswork for anyone using a scale.

Where linear scaling breaks

The formula multiplies everything by the same number, and four things do not obey it.

Leavening is the first. Using the full calculated amount of baking powder or yeast in a large batch over-leavens the mixture. Take 75 percent of the calculated figure and watch the first bake.

Salt and strong spices are the second. Their flavour intensifies as liquid reduces, so a large batch wants about 75 percent of the calculated amount for salt and 60 to 75 percent for spices. Tasting at the end of cooking is the only reliable check.

Eggs are the third, because a fractional egg is awkward. Three eggs scaled by 1.5 is 4.5 eggs. Beat the egg and weigh or measure half of it, which is about 25 millilitres, or adjust the other liquids slightly.

Cooking time is the fourth. Doubling a pot of soup does not double the time, because the pot still heats at the same rate and the volume only has further to travel. A larger tin needs a little more time and a check for doneness well before the stated end.

Serving factors worth knowing

The factor is the target serving count divided by the original.

The 6 to 15 row is a 150 percent increase, which is a large enough jump that the leavening and salt adjustments stop being optional. The 12 to 3 row is the same factor upside down, and it is the safer direction, because scaling down rarely changes how a mixture behaves.

Units and rounding

The scaler multiplies a number and a unit. It does not convert between units, so a recipe listing 250 g of flour and 1 cup of milk scales each figure in its own terms and leaves you with both.

For weights, hold the full precision until the end and round once. A recipe needing 1,625 g of water is easy. A recipe needing 16.25 g of yeast is easier to weigh on a scale that reads to 0.1 g than to measure in spoons.

For volumes, rounding to the nearest quarter spoon or the nearest 5 millilitres keeps the measurement usable. Rounding to three decimal places produces numbers no kitchen can act on.

Where the baking references come from

The definition of baker's percentage, that each ingredient is expressed as a percentage of the flour weight and the flour weight is always 100 percent, comes from the baker's percentage reference published by King Arthur Baking, fetched on 14 September 2026. The same page introduces the formula conversion factor used for scaling a formula up or down.

The teaspoon and tablespoon figures of 5 and 15 millilitres are the standard metric definitions. The tin areas, volumes, spoon conversions and conversion factors in this section were all computed for this page from the formulas above.

Also try these free tools:

• Nutrition Label Generator
• Cooking Time Calculator
• Safe Cooking Temperatures