Use ratios to adjust any recipe to the serving size you need
The Scaling Factor
Scaling factor = Desired servings ÷ Original servings
Multiply every ingredient by this factor.
Recipe serves 4, you need 6
Scaling factor: 6 ÷ 4 = 1.5
Multiply every ingredient by 1.5
2 cups flour → 2 × 1.5 = 3 cups
3 eggs → 3 × 1.5 = 4.5 eggs (round to 4 or 5)
Scaling Down
Recipe serves 8, you need 2
Scaling factor: 2 ÷ 8 = 0.25 (or ÷4)
4 cups sugar → 4 × 0.25 = 1 cup
1 cup butter → 1 × 0.25 = ¼ cup
Practical Tips
Eggs: If a calculation gives you a fraction (like 1.5 eggs), round to the nearest whole number or use the "slightly beat an egg and measure half" method. Spices: Don't scale linearly for large increases — doubling a recipe doesn't always mean doubling the salt. Start with 1.5× for a 2× recipe and adjust.
💡 Using proportions instead: If a recipe uses 3 cups flour for 24 cookies, and you want 36 cookies: 3/24 = x/36 → x = 4.5 cups. Same result, different approach.
🎯 Practice Problems
1. A recipe serves 4 and calls for 2 cups of rice. How much rice for 10 servings?
A) 4 cups
B) 5 cups
C) 8 cups
D) 20 cups
2. A recipe for 12 cookies uses 1.5 cups of flour. How much flour for 8 cookies?
A) 0.5 cups
B) 0.75 cups
C) 1 cup
D) 1.25 cups
3. You want to triple a recipe that uses ½ cup of sugar. How much sugar?
A) 1 cup
B) 1¼ cups
C) 1½ cups
D) 2 cups
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🎯 Bonus Practice
1. A recipe serves 6 and uses 4 eggs. How many eggs for 9 servings?
A) 5
B) 6
C) 8
D) 12
2. A smoothie recipe for 2 uses 3 cups of fruit. How much for 5 smoothies?
A) 6 cups
B) 7.5 cups
C) 10 cups
D) 15 cups
3. A cake recipe serves 8 and uses 3 cups flour. You're cutting it in half. How much flour?
A) 1 cup
B) 1.5 cups
C) 2 cups
D) 6 cups
4. Recipe: 2 tbsp oil for 4 servings. How much oil for 1 serving?
A) 0.25 tbsp
B) 0.5 tbsp
C) 1 tbsp
D) 2 tbsp
5. A recipe uses 250g butter for 20 brownies. How much butter for 30 brownies?