Ratio Calculator
Solve proportions and find missing ratio values.
⚖️ Solves proportions. Example: 3/4 = 9/D → D = 12. Useful for recipes, scaling, and maps.
What Is This Tool?
A ratio compares two quantities, like 3:2 or 5 to 4. This calculator solves proportions — given three values of A:B = C:D, it finds the fourth. It also simplifies ratios to lowest terms.
How Proportions Work
In a proportion A:B = C:D, the cross products are equal: A × D = B × C. So if you know any three values, you can solve for the fourth. To find D: D = (B × C) ÷ A.
Common Uses
- Recipes: Scaling a recipe from 4 servings to 6
- Maps: 1 inch = 50 miles → how far is 3.5 inches?
- Business: Revenue per employee, profit margins
- Photography: Aspect ratios like 3:2 or 16:9
- Construction: Mixing concrete at 1:2:3 ratios
Example
A recipe serves 4 and uses 2 cups of flour. How much flour for 6 servings? Set up the proportion 4:2 = 6:D. Solving: D = (2 × 6) ÷ 4 = 3 cups.
Frequently Asked Questions
What if my ratio has decimals?
This calculator handles decimals fine. To work with whole numbers, multiply both sides by 10 or 100 to remove decimals first.
About the Ratio Calculator
The Ratio Calculator lets you figure out ratio calculatorinstantly, without reaching for a spreadsheet or doing the math by hand. Whether you're planning a budget, checking a loan, or working through homework, the tool applies the correct formula behind the scenes and shows the result the moment you enter your numbers.
Unlike a static chart or table, this calculator adapts to your exact inputs. You can adjust any value and see the outcome update in real time, which makes it easy to compare scenarios — for example, "what if the rate were 1% lower?" or "what if I paid an extra $50 a month?"
How to Use This Tool
- Enter the main values the calculator asks for (for example, amount, rate, and time).
- Pick the right unit or option where the tool offers a choice.
- Read the result, which appears instantly below the inputs.
- Adjust any field to test a different scenario — the answer updates without a reload.
- Copy or note the result. Nothing is stored, so close the tab when you're done.
Why Use an Online Calculator?
Browser-based tools like this one have a few real advantages over installed software or manual methods:
- No installation. It opens instantly in any browser, on any operating system.
- Private by default. Everything runs locally, so your data stays on your device.
- Always up to date.There's nothing to update — you always get the latest version when you load the page.
- Free and unlimited. Use it as often as you like, with no account and no caps.
Related Tools
More tools you might find useful
Prime Factorization Calculator
Decompose any number into its prime factors.
Average Calculator
Calculate mean, median, sum, min, max, and range of any number list.
Scientific Notation Converter
Convert numbers to scientific, E-, and engineering notation.
Sort Text Lines
Sort any list alphabetically in one click.
HTML Unescape
Convert HTML entities back to readable characters.
Debt-to-Income Calculator
Calculate DTI ratio and see if lenders will approve you.