Free online ratio calculator
A ratio compares two quantities by division. This calculator simplifies ratios to lowest terms, shows the decimal equivalent, and solves proportion problems.
: A : B
Used to solve A:B = x:C or A:B = C:x
Saved to favorites
Your favorites are on the home page under “Your favorites.” They are saved only in this browser on this device, so they will not appear on another device or browser. No account, no server.
How to use
- Enter values for A and B.
- Optionally enter C to solve proportions (A:B = x:C or A:B = C:x).
- Click Calculate.
- See the simplified ratio, decimal form, and proportion solutions.
Formulas
Simplified ratio: Divide both terms by GCD(A, B).
Decimal: A ÷ B
Proportion (x:C): x = A × C ÷ B
Proportion (C:x): x = B × C ÷ A
Worked example
Ratio 6:8:
- GCD(6, 8) = 2
- Simplified: 6÷2 : 8÷2 = 3:4
- Decimal: 6÷8 = 0.75 (75%)
Proportion: 3:4 = x:12
- x = 3 × 12 ÷ 4 = 9
- So 3:4 = 9:12 ✓
References
Frequently asked
How do you simplify a ratio?
Find the greatest common divisor (GCD) of both numbers and divide each by it. For 6:8, GCD is 2, so 6÷2 = 3 and 8÷2 = 4, giving simplified ratio 3:4.
What is a proportion?
A proportion states that two ratios are equal. If A:B = x:C, then x = A×C÷B. For example, if 3:4 = x:12, then x = 3×12÷4 = 9.
What is the decimal form of a ratio?
The decimal form of A:B is A÷B. For 3:4, the decimal is 3÷4 = 0.75, which equals 75%.
Can ratios have decimal or fractional parts?
Yes. A ratio like 1.5:2 is equivalent to 3:4. The calculator handles decimal inputs and simplifies them to integer form.
What is a three-term ratio?
A three-term ratio like 2:3:5 compares three quantities simultaneously. It can describe mixtures, scales, or divisions. For example, to split $1,000 in a 2:3:5 ratio, multiply each part by 1000÷10.
Embed this calculator
Add this free calculator to your own site. Copy the snippet — it works anywhere you can paste HTML, and stays in sync with this page.