CalculynHow it works
Two ratios are in proportion when their cross products are equal. Solve for the unknown by cross-multiplying.
Formula
A : B = C : D → D = B × C ÷ A
Example
3 : 4 = 15 : ? → ? = 4 × 15 ÷ 3 = 20.
Assumptions & limitations
- Results are rounded for display.
Frequently asked questions
How do I scale a recipe?
Set A to the original servings, B to an ingredient amount, and C to the servings you want.