01
Half of 300 g
A list for four uses 300 g. How much for two?
Work it through
150 g2 ÷ 4 = 1/2. Multiply 300 g by 1/2 to get 150 g.
Play & Practice / Recipe Math Lab
Make room for one more.
Change the number of servings and watch each ingredient follow the same proportion.
Try the calculator ↓
01 / Set the question
Same proportions.
A different amount.
These are arithmetic examples, not tested recipes. US household units stay in their original units; grams measure mass and milliliters measure volume.
You can edit every ingredient below to make your own small list (up to 12). Only ingredient quantities are calculated.
Scale factor2×
4 ÷ 2 = 2
Original · 2
Desired · 4
02 / Original → Scaled
Cooked chickpeas
240 g scales to 480 g
Calculation: 240 × (4 ÷ 2) = 480 g. Display rounded to at most 3 decimals; very small quantities use 3 significant figures.
Lemon
1 count scales to 2 count
Calculation: 1 × (4 ÷ 2) = 2 count. Display rounded to at most 3 decimals; very small quantities use 3 significant figures.
Cooking oil
1 1/2 US tbsp scales to 3 US tbsp
Calculation: 1.5 × (4 ÷ 2) = 3 US tbsp. Display rounded to at most 3 decimals; very small quantities use 3 significant figures.
Seasoning
to taste scales to to taste
This instruction stays as text; it is not a zero quantity.
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03 / Put the idea to work
Six small challenges.
02
Double a fraction
Double 3/4 US cup.
Work it through
1 1/2 US cups3/4 × 2 = 6/4 = 1 1/2. The unit remains US cups.
03
A fractional factor
Go from 4 servings to 6. Scale 200 mL.
Work it through
300 mL6 ÷ 4 = 1.5; 200 mL × 1.5 = 300 mL. Bigger does not always mean double.
04
Part of a count
A list for 4 calls for 1 lemon. What does the arithmetic say for 3?
Work it through
0.75 lemon3 ÷ 4 = 0.75. Arithmetic can produce part of an item. A suitable recipe must explain how to measure or divide it; silently rounding changes the proportion.
05
Ounces of what?
Can 4 oz of flour be replaced automatically by 4 US fl oz?
Work it through
NoOunces here measure mass; US fluid ounces measure volume. The same number does not make them equivalent. This tool never converts between them.
06
Keep the original
Scale 1/3 g from 3 servings to 5, then back to 3. Does rounding the display change the original?
Work it through
No; the original stays 1/3 gEvery calculation uses the original 1/3, not the previous rounded result. Display rounding is for reading. Cooking time and temperature are never part of this multiplication.