Ratio Calculator Online Free Tool
Ratio Calculator
Ratio Calculator
Please provide any three values below to calculate the fourth in the ratio A:B = C:D.
Ratio Scaling Calculator
Scale a ratio up or down by a specific factor.
A ratio compares two or more quantities, showing their relative sizes. Ratios appear everywhere from cooking recipes to map scales to financial analysis. This calculator simplifies ratios, solves ratio proportions, scales ratios up or down, and converts between ratio and percentage forms.
Working with Ratios
A ratio of 2:3 means for every 2 of the first quantity there are 3 of the second. To simplify a ratio, divide both numbers by their greatest common factor (GCF). To scale a ratio, multiply both numbers by the same factor. To check if two ratios are proportional (equivalent), cross-multiply and check if the products are equal.
Simplify: Divide both parts by GCF Scale: Multiply both parts by the same number Proportionality test: If a:b = c:d, then a×d = b×c
Example: 4:6 simplifies to 2:3 (divided by GCF of 2).
Practical Ratio Applications
Ratios are used in cooking (double a recipe), mixing (paint colors, concrete), scale models, maps, and financial analysis (price-to-earnings ratio, debt-to-equity). Understanding ratios is fundamental to proportional reasoning.
| Application | Example Ratio |
|---|---|
| Cooking (recipe scaling) | 1 cup flour : 2 eggs |
| Concrete mix | 1 cement : 2 sand : 3 gravel |
| Map scale | 1 cm : 50,000 cm (0.5 km) |
| Financial (P/E ratio) | Stock price : Annual earnings per share |
Frequently Asked Questions
What is the difference between a ratio and a fraction?⌄
A fraction represents one part out of a whole (3/4 means 3 out of 4 total). A ratio compares two separate quantities to each other (3:4 means 3 of one thing for every 4 of another). The ratio 3:4 can be written as the fraction 3/4, but the meanings differ in context.
How do I solve a proportion?⌄
A proportion is two equal ratios: a/b = c/d. To find a missing value, cross-multiply: if x/5 = 4/10, then 10x = 20, so x = 2. This technique is called cross-multiplication and works because multiplying both sides of the equation by both denominators gives the same result.
How do I divide a number in a given ratio?⌄
Add the ratio parts to find the total shares. Divide the number by the total shares to find one share. Multiply each ratio part by one share. Example: divide 60 in ratio 2:3. Total shares = 5. One share = 60/5 = 12. Result: 24 and 36.
What is a unit ratio?⌄
A unit ratio simplifies one side to 1. Instead of 3:6, you write 1:2. Instead of 5:15, you write 1:3. Unit ratios make comparisons easier and are similar to unit rates (miles per hour, cost per unit) used in everyday contexts.