A ratio calculator solves proportion problems: if a:b = c:d, and three values are known, find the fourth.
About this calculator
A ratio calculator solves proportion problems: if a:b = c:d, and three values are known, find the fourth. Ratios and proportions show up in everyday situations: scaling recipes, converting units, map reading, and keeping a consistent relationship between values.
Cross-multiplication is the underlying method: a/b = c/d means a × d = b × c, so d = b × c / a.
Common uses
- Scale a recipe from 4 servings to 10 servings
- Calculate real-world distances from a map with a known scale
- Convert units using known conversion ratios
- Solve proportion word problems from school or work
Frequently asked questions
How do you solve a ratio proportion?
Cross-multiply: If a/b = c/d, then d = (b × c) / a. For example, if 3 kg costs ₹150, how much does 7 kg cost? 3/150 = 7/x. x = (150 × 7) / 3 = 1050 / 3 = ₹350.