Advanced Ratio Calculator
Enter a ratio to simplify
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Solve: A : B = C : X
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=
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Compare two ratios
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Please enter valid, non-zero numbers in all fields.
Quick Reference
Common Ratios to Percentage & Fraction
Handy conversions for ratios you'll see often — in recipes, finance, and design.
| Ratio | Fraction | Percentage Split |
|---|---|---|
| 1:1 | 1/2 each | 50% / 50% |
| 1:2 | 1/3 : 2/3 | 33.3% / 66.7% |
| 1:3 | 1/4 : 3/4 | 25% / 75% |
| 2:3 | 2/5 : 3/5 | 40% / 60% |
| 3:4 | 3/7 : 4/7 | 42.9% / 57.1% |
| 4:5 | 4/9 : 5/9 | 44.4% / 55.6% |
| 16:9 | — | Widescreen aspect ratio |
The Method
How Each Mode Works
Simplify
Divide both A and B by their Greatest Common Divisor (GCD)
Solve for X (Cross Multiplication)
A : B = C : X
X = (B × C) ÷ A
Compare
A : B vs C : D
Compare A × D against B × C
Worked Example
Step-by-Step: Solve for X
A recipe uses flour and sugar in a 3:2 ratio. If you use 9 cups of flour, how much sugar do you need?
Set up the proportion: 3 : 2 = 9 : X
Cross multiply: X = (2 × 9) ÷ 3
Solve: X = 18 ÷ 3 = 6 cups of sugar
Who Uses This
Common Ways People Use This Calculator
Cooking
Scale recipes up or down
Finance
Debt-to-income, P/E ratios
Maps & Models
Scale drawings and blueprints
Mixing
Paint, concrete, and solutions
Aspect Ratios
Photo, video and screen sizing
Education
Learn ratios and proportions
Engineering
Gear, design and scale ratios
Science
Chemical and laboratory mixtures
Get It Right
Tips for Working with Ratios
Keep Units Consistent
Both sides of a ratio must use the same unit — don't mix cups with grams without converting first.
Order Matters
3:2 is not the same as 2:3 — always keep the same order on both sides of a proportion.
Simplify Before Comparing
Reduce ratios to their simplest form to make comparisons quicker and easier.
Cross-Check with a Fraction
Convert a ratio to a fraction or percentage to verify your calculations.
Use Whole Numbers
Multiply or divide both parts equally to remove decimals while keeping the ratio equivalent.
Double-Check Inputs
Even a small typing mistake can change the final ratio, so review your values before calculating.
Questions
Frequently Asked Questions
Find the greatest common divisor (GCD) of both numbers and divide each side by it. For example, 12:18 simplifies to 2:3 because their GCD is 6.
Cross multiply: X = (B × C) ÷ A. Our "Solve for X" mode does this instantly for you.
Cross multiply both ratios and compare the results — for A:B vs C:D, compare A×D against B×C. Our "Compare" mode handles this automatically.
Add both parts of the ratio together to get the total, then divide each part by that total and multiply by 100. For 1:3, the total is 4, so it's 25% and 75%.
Yes — ratios like 2:3:5 are common in recipes and mixing (e.g. cement:sand:aggregate). This calculator focuses on two-part ratios, the most common case.
A ratio compares two separate quantities (like flour to sugar), while a fraction represents a part of a whole. They're related but used differently — a ratio of 1:3 corresponds to fractions of 1/4 and 3/4 of the total.
Keep the original ratio between ingredients fixed, then use "Solve for X" with your new target quantity for one ingredient to find the matching amount for the other.
No. All calculations run in your browser — nothing you enter is sent to or stored on our servers.
The simplest form is obtained by dividing both numbers by their greatest common divisor (GCD). For example, 20:30 becomes 2:3.
Yes. However, it's usually easier to multiply both sides by the same number to remove decimals before simplifying.
In most practical situations such as finance, recipes and measurements, ratios are positive values. Negative ratios are mainly used in mathematics.
Equivalent ratios represent the same relationship. For example, 2:3, 4:6 and 10:15 are all equivalent ratios.
Divide the first number by the second. For example, the ratio 3:4 equals the decimal value 0.75.
Ratios are used in cooking, finance, construction, engineering, photography, map scales, chemistry and many everyday calculations.
Yes. Simplify each ratio or convert them to decimal values to compare multiple ratios accurately.
Simplified ratios are easier to understand, compare and use in calculations while representing the exact same relationship.
Yes. Enter three known values in a proportion and the calculator instantly finds the missing value using cross multiplication.
The calculator performs precise mathematical calculations instantly. Results are accurate based on the values you enter.
Yes. The Ratio Calculator is fully responsive and works on smartphones, tablets, laptops and desktop computers.
Yes. You can use the calculator as often as you like without registration, subscriptions or hidden charges.
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