Ratio Calculator
This ratio calculator helps you simplify ratios and find equivalent values. Enter your numbers to calculate and compare ratios easily. Useful for math, recipes, business, and financial analysis.
Ratio Values
Simplified Ratio
Enter values to simplify the ratio.
How Ratios Work
A ratio compares two quantities and shows their relative size. The ratio 4:6 means "for every 4 of the first thing, there are 6 of the second." Simplifying a ratio means dividing both numbers by their greatest common divisor (GCD). For 4:6, the GCD is 2, giving the simplified ratio 2:3. This is equivalent but easier to read and reason about.
Ratios appear in recipes (2 parts flour to 1 part sugar), finance (debt-to-equity of 1.5:1), maps (scale of 1:50,000), and aspect ratios for screens (16:9). The decimal form of a ratio is simply the first number divided by the second — 4:6 = 0.667, meaning the first quantity is 66.7% the size of the second.
Financial Ratios You Should Know
In finance, ratios are essential analysis tools. The price-to-earnings (P/E) ratio compares stock price to annual earnings — a P/E of 20:1 means you are paying $20 for every $1 of annual profit. The debt-to-income ratio used in mortgage lending compares monthly debt payments to monthly gross income — lenders typically want this below 43%. The current ratio (current assets : current liabilities) measures a company's ability to pay short-term bills; a ratio above 1.5:1 is generally considered healthy.
Frequently Asked Questions
What is the difference between a ratio and a fraction?
A fraction represents a part of a whole — 3/4 means 3 out of 4 equal parts. A ratio compares two separate quantities that may or may not be parts of the same whole — 3:4 means "3 compared to 4." A ratio can be converted to a fraction (3:4 = 3/4) and vice versa, but context matters. If you mix 1 cup of juice with 3 cups of water, the juice-to-water ratio is 1:3, but juice is 1/4 of the total drink. Both statements are correct and mean different things.
How do I scale a ratio up or down?
Multiply or divide both parts of the ratio by the same number. To scale a 2:3 ratio to make 10 total parts, multiply both by 2 to get 4:6 (or keep 2:3 but use it in units of 2, giving 4 of the first and 6 of the second). For recipes, if a 2:3 flour-to-sugar ratio makes 10 cookies and you want 25, multiply by 2.5 to get a 5:7.5 ratio. Always keep both numbers changing by the same factor to preserve the proportion.
How do I find a missing value in a proportion?
If two ratios are equal (a proportion), you can cross-multiply to find an unknown. For example: if 3:4 = x:20, then 3 × 20 = 4 × x, so 60 = 4x, and x = 15. This is useful in many practical situations — scaling recipes, calculating map distances from scale, finding equivalent exchange rates, and working out dilution ratios for cleaning products or paints. Cross-multiplication works any time two ratios are set equal to each other.