Ratio Calculator
Solve ratios and proportions (A:B = C:?), simplify ratios like 12:18 or 1.5:2.25, and split an amount in a ratio with this free online ratio calculator.
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Free, no sign-up, works in the browser — send it to a friend or add it to your site.
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Part of the toolkit
How to use Ratio Calculator
- 1Pick a mode: solve a proportion, simplify a ratio, or split an amount
- 2Enter your numbers — for a proportion, leave the unknown box empty
- 3Read the answer with the working shown, and copy it
Frequently asked questions
How do you solve a ratio or proportion?▾
Cross-multiply. For A : B = C : D, A × D = B × C, so the missing value is the product of the two diagonal numbers divided by the one opposite it. For 3 : 4 = 15 : ?, ? = 4 × 15 ÷ 3 = 20.
How do you simplify a ratio?▾
Divide every part by their greatest common factor. 12 : 18 has a GCF of 6, so it simplifies to 2 : 3. With decimals, multiply all parts by 10, 100… first to make whole numbers: 1.5 : 2.25 → 150 : 225 → 2 : 3.
How do I divide an amount in a ratio?▾
Add the ratio parts to get the number of shares, divide the total by that number to get one share, then multiply by each part. 1,200 in the ratio 2 : 3 : 5 is 10 shares of 120 — so 240, 360 and 600.
What is the difference between a ratio and a fraction?▾
A ratio compares parts to each other (2 red : 3 blue), while a fraction compares a part to the whole (2⁄5 of the balls are red). The ratio 2 : 3 means the red share is 2⁄5 of the total.
Are 2:3 and 4:6 the same ratio?▾
Yes — they're equivalent ratios, because 4 : 6 simplifies to 2 : 3. Multiplying or dividing every part by the same number keeps the ratio the same.
Where are ratios used in real life?▾
Recipes and scaling ingredients, mixing paint, concrete or fuel, map scales, screen aspect ratios, sharing money or profits, and dosage calculations.
Embed Ratio Calculator on your website▾
Paste this snippet into your page. The embedded tool runs in your visitor's browser and shows a small “Powered by clkr.work” link.