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About this tool
Simplify ratios, solve for a missing term and split a total in any given ratio.
Ratio Calculator handles the three things people actually need from ratios: reducing one to its simplest whole-number form, solving a proportion like 3 : 4 = 12 : ? for the missing term, and dividing a total in a given ratio such as 2 : 3 : 5. It reduces using the greatest common divisor and scales decimal terms to whole numbers first, so 1.5 : 2 correctly becomes 3 : 4. Every mode shows the working — scale factor, sum of parts, value of one part and each term's percentage share.
Open Ratio Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Simplify, solve a proportion, or split a total without switching tools.
Decimal terms are scaled to integers before reducing, so 1.5 : 2 gives an exact 3 : 4.
Scale factor, cross-product check, value of one part and percentage shares are all displayed.
Divide every term by the greatest common divisor of all the terms. For 1920 : 1080 the GCD is 120, which reduces the ratio to 16 : 9.
In a : b = c : d, cross-multiply so a x d = b x c. Solving for the missing fourth term gives d = (b x c) / a — for example 3 : 4 = 12 : d gives d = (4 x 12) / 3 = 16.
Add the parts (2 + 3 + 5 = 10), divide the total by that sum to get the value of one part, then multiply each part by it. A total of 5,000 splits into 1,000, 1,500 and 2,500.
Yes. Simplify mode accepts a third term, and split mode accepts as many parts as you type separated by colons, commas or spaces.
Add the Ratio Calculatorwidget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
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