Recipe Scaler

How to use the recipe scaler

1. Type or paste the ingredients into the box, one ingredient per line, with the amount at the start of the line. A recipe name is optional and is printed above the list.
2. Under Original size, enter how many servings the recipe makes as written. Under Resize to, enter how many you want. Leave both empty to convert units without changing the quantities.
3. Choose the output metrics. Same as source keeps the units you wrote, Imperial moves metric amounts to ounces and pounds, and Metric moves ounces, pounds and fluid ounces to grams and millilitres.
4. Decide whether spoons and cups should be converted too. By default they are left as written.
5. Press Scale Recipe. The result is plain text, ready to copy into a note or a message.

The tool works on the text you give it. It cannot fetch a recipe from a web page, so copy the ingredient list across first.

How to write the ingredient lines

Each line is read from the left. The scaler looks for an amount first and multiplies it; everything after the amount is copied back unchanged.

• Whole numbers, decimals and fractions are all understood: 2, 1.5, 3/4, and mixed numbers such as 1 1/2.
• The single-character fractions ½ ¼ ¾ ⅓ ⅔ ⅛ and so on are understood too, including when attached to a whole number (1½).
• Ranges written with a hyphen or the word to are scaled at both ends: 2-3 apples or 1/2 to 1 cup.
• A line that does not begin with an amount ("salt to taste", "a pinch of nutmeg", "one cup flour") is left alone.
• Only the amount at the start of a line is scaled (a range counts as one amount). Numbers in brackets, such as the weight in 2 cups (250 g) flour, are left as they are.
• Put a space between a fraction and the unit: 1/2 tsp, not 1/2tsp.

Scaled amounts are shown as fractions rather than long decimals, so one third of a cup stays 1/3 cup instead of 0.3333 cup. When a recipe name is entered it appears at the top, followed by a line of dashes.

How the scaling works

Every amount is multiplied by the same scaling factor, which is the new number of servings divided by the original number:

scaling factor = new servings ÷ original servings

Example: a recipe for 4 that you want to serve 6 people has a factor of 6 ÷ 4 = 1.5. Two cups of flour become 3 cups, 1 1/2 teaspoons of salt become 2 1/4 teaspoons, 3 eggs become 4 1/2 eggs and 200 g of sugar becomes 300 g.

Scaling down works the same way: going from 6 servings to 4 gives a factor of 2/3, so 2 cups of flour become 1 1/3 cups and 200 g of sugar becomes 133 1/3 g.

The scaler also adjusts a handful of common words to match the new amount: cup, tablespoon, teaspoon, ounce, pound, gram, pint, quart, gallon, egg, clove and can get an s above one and lose it at one or less. Other nouns are copied exactly as typed, so check phrases such as "3 onion" yourself. Amounts of grams or millilitres above 1000 are re-expressed as kilograms or litres.

Converting between metric and US units

Unit conversion happens after scaling, on the unit that directly follows the amount. Metric results are rounded to whole grams and millilitres. US results are shown to the nearest eighth.

Example: 8 oz of cheese becomes 8 × 28.35 = 226.8, shown as 227 g, and 12 fl oz of stock becomes 354.9, shown as 355 ml. For the other direction, 100 g of butter becomes 3 1/2 oz and a cup of milk becomes 8 fl oz when the output is set to imperial and spoons and cups are converted.

Cups, tablespoons and teaspoons are converted by volume using the metric kitchen values above (a 250 ml cup), not by weight. A cup of flour weighs far less than a cup of sugar or butter. To turn a cup of a particular ingredient into grams, use the cups to grams converter.

What does not scale in a straight line

A multiplier is exact for quantities, but cooking is not purely proportional. Keep these in mind when you scale a recipe a long way up or down:

• Salt, spices and strong flavours. Doubling is usually fine, but past a factor of three or four, start with a smaller multiple and taste before adding more.
• Cooking and baking time. A bigger batch in a bigger pan usually takes longer. Watch for doneness (colour, texture, a probe thermometer) rather than trusting the original timing.
• Pan and pot size. Doubling a cake batter in the same pan makes a deeper cake that bakes unevenly. Use a larger pan or two pans of the original size.
• Odd fractions of an egg. Beat the egg, then measure out the portion by weight or spoonfuls. A large egg without its shell is roughly 50 g.
• Leavening. Baking powder, baking soda and yeast sometimes need a little less than the straight multiple in very large batches. Test before cooking for a crowd.

Related conversions

If a recipe lists ingredients you would rather weigh, or you need to move between volume and weight, these converters help: the recipe converter, cups to grams, grams to cups, cups to ml and grams to ml.