Numbers › Ratios

Ratios & proportion

A ratio compares two amounts. Scale them both and the ratio holds.

Ratio 2 : 1 — flour : sugar

Slide to scale the recipe. The ratio stays the same.

Flour

2 cups

Sugar

1 cups

2 : 1(still 2 : 1)

What stays the same

The ratio 2 : 1 is the same as 4 : 2, 6 : 3, 10 : 5. You're just multiplying both sides by the same number — the relationship between the two amounts hasn't changed.

A proportion is two ratios that match

If 2 cups flour : 1 cup sugar makes one cake, then 6 : 3 makes three. The proportion 2/1 = 6/3 tells you the recipe scaled up cleanly.