Free Ratio Calculator
Solve any ratio in seconds. Simplify ratios, scale a ratio to a total, find a missing value, compare proportions, or convert ratio parts to percentages. Ideal for students, recipes, mixing, budgets, and business splits.
How to Use
- Choose Simplify, Scale / split, Missing value, Percentages, or Compare.
- Enter the ratio using colons, commas, slashes, or spaces. Multi-part and decimal ratios are supported.
- Select Calculate to see the answer, a visual ratio bar, and clear worked steps.
- Copy the result or switch modes to solve another ratio problem.
Features
- Simplify two-part and multi-part ratios to lowest terms
- Scale a ratio to a target total or split an amount fairly
- Find any missing value in a proportion
- Convert every ratio part to its percentage share
- Compare two ratios and check whether they are equivalent
- Decimal input, visual ratio bars, examples, and worked steps
How to Scale a Ratio to a Total
To scale a ratio, add its parts, divide the target total by that sum, and multiply each part by the result. For a 3:5 ratio scaled to 400, there are 8 total parts. Each part is worth 400 ÷ 8 = 50, so the scaled ratio is 150:250.
Use Scale / split when dividing budgets, ingredients, mixtures, profits, or any other total in a fixed proportion. The calculator also supports ratios with more than two parts.
How to Find a Missing Part of a Ratio
Write the ratios as a proportion: A:B = C:D. Enter three known values and leave the unknown box empty. The calculator cross-multiplies and rearranges A × D = B × C to solve the blank.
For example, if 2:3 = 10:x, then x = (3 × 10) ÷ 2 = 15. The completed proportion is 2:3 = 10:15.
How to Simplify a Ratio
Find the greatest common divisor of all parts, then divide every part by it. For 18:24, the greatest common divisor is 6, so 18 ÷ 6 : 24 ÷ 6 gives the simplified ratio 3:4.
This calculator can also simplify decimal and multi-part ratios. It first converts decimals to equivalent whole numbers, then reduces every part by the same common divisor.
How to Convert a Ratio to a Percentage
Add all ratio parts to find the whole. Divide each part by that whole and multiply by 100. In the ratio 3:5, the total is 8, so the shares are 3 ÷ 8 × 100 = 37.5% and 5 ÷ 8 × 100 = 62.5%.
The percentages always total 100%, apart from tiny display differences caused by rounding. The visual ratio bar makes each share easy to compare.
Practical tips for Ratio Calculator
Before you start, keep your source ready and decide what “done” looks like — a downloaded file, copied text, or a converted format. Ratio Calculator works best when the input is clear and complete.
If the first result is close but not perfect, adjust one setting at a time and compare again. That is usually faster than restarting from scratch.
Frequently Asked Questions
How do I calculate the ratio between two numbers?
Enter both numbers in the Simplify mode. The calculator divides them by their greatest common divisor and returns the ratio in lowest terms.
How do I scale a ratio to a total?
Choose Scale / split, enter the ratio and target total, then calculate. The tool divides the total by the sum of the ratio parts and scales every part proportionally.
How do I find a missing value in a ratio?
Choose Missing value, enter three values in A:B = C:D, and leave exactly one box blank. The calculator uses cross-multiplication to solve it.
How do I simplify a ratio to lowest terms?
Divide every part by their greatest common divisor. The Simplify tool performs this automatically and also supports decimal and multi-part ratios.
How do I convert a ratio to a percentage?
Choose Percentages. Each ratio part is divided by the sum of all parts and multiplied by 100 to show its share of the whole.
What is the difference between a ratio and a proportion?
A ratio compares quantities, such as 2:3. A proportion states that two ratios are equal, such as 2:3 = 10:15.
Is this ratio calculator free?
Yes. It is free, requires no sign-up, and performs calculations directly in your browser.
