How to use the recipe scaler
- Choose Change the servings, or Multiply by a number to halve, double or triple.
- Type Original servings (what the recipe makes) and New servings (what you want). With a multiplier, use Multiply every amount by or press Halve, Double or Triple.
- Paste your list into Ingredients, one per line, amount first, like
1 1/2 tsp salt. - Leave Tidy units ticked to switch to the unit a cook would reach for, or clear it to keep your units.
- Read the Scaled column, then press Copy scaled list.
How the amounts are worked out
The scaling factor is new servings divided by original servings, and the amount at the start of each line is multiplied by it. Fractions (3/4), mixed numbers (1 1/2), symbols (½, 1½), decimals, ranges (2-3) and sums such as 1 cup + 2 tbsp are all read as numbers.
Cup and spoon amounts show the nearest kitchen fraction (eighths and thirds) when it is within 0.02 of the true value, otherwise a two-decimal number. A leading ≈ marks a rounded fraction. Metric amounts stay decimal, so 100 g times 1.333 reads 133 g, never 133 ⅓ g.
Tidy units uses the exact U.S. relationships in NIST Handbook 44: 3 teaspoons make a tablespoon, and a cup is 8 fluid ounces, so 16 tablespoons make a cup. That is why 3 tsp becomes 1 tbsp, 8 tbsp becomes ½ cup and 1,000 g becomes 1 kg. It switches only when the result is an amount you can measure.
Worked example
The defaults scale 4 servings to 6, a factor of 6 ÷ 4 = 1.5:
- 2 cups flour becomes 3 cups flour
- 1 1/2 tsp salt becomes 2 ¼ tsp salt
- 3/4 cup sugar becomes 1 ⅛ cups sugar
- 2 large eggs becomes 3 large eggs
- 1 cup milk becomes 1 ½ cups milk
- 0.25 cup butter becomes 6 tablespoons butter
The butter works out to 0.375 cup. ⅜ cup is not a standard measure, so Tidy units shows 6 tablespoons. Clear the box and it reads ⅜ cup.
Limits and edge cases
- Only the amount at the start of a line is scaled.
flour, 2 cupsis left alone, and numbers in brackets, like a 14 oz can, never change. - Pan sizes, times and temperatures stay put. So do headings and step numbers.
- Whole items need a decision. If 2 eggs become 2 ½, the line tells you to round or split one.
- Big changes are not straight lines. Past 2× or under ½×, salt, spices, leavening and liquid often need less than a straight multiple, and pan size changes the cooking time.
- U.S. cups and spoons. Use the cooking measurement converter for other systems, the oven temperature converter for oven settings and baking substitutions when you run short.
Recipe scaler FAQ
How do I scale a recipe up or down?
Divide the servings you want by the servings the recipe makes, then multiply every ingredient by that number. Going from 4 servings to 6 is 6 ÷ 4 = 1.5, so 2 cups becomes 3 cups.
How do I double or halve a recipe?
Choose Multiply by a number, then press Double (2×) or Halve (0.5×). You can also enter the servings, such as 4 and 8 to double.
How do I halve a recipe that calls for one egg?
Beat the egg and use half. A beaten large egg measures about 3 tablespoons, so half is about 1 1/2 tablespoons.
Do cooking times change when I scale a recipe?
Often, but not in step with the amounts. A bigger batch in the same pan takes longer and a smaller one cooks faster. Keep the oven temperature and check early.
Why did a line stay the same?
Only an amount at the start of a line is scaled. Headings, notes like salt to taste, step numbers, sizes, times and temperatures are copied unchanged.
Sources: NIST Handbook 44 (2026), Appendix C; NIST Metric Kitchen equivalents. Advice on leavening, seasoning and equipment follows general culinary practice.