Ratio Calculator
Enter two values to simplify their ratio, or scale it proportionally to a new value.
Enter a new value for A to scale B proportionally.
Simplified ratio
2 : 3
Decimal equivalent
1
How to use the Ratio Calculator
- Enter the two values of your ratio (A and B).
- See the simplified ratio and its decimal equivalent instantly.
- Optionally, enter a new value for A to scale B proportionally.
What is a ratio calculator?
A ratio calculator reduces a ratio like 8:12 down to its simplest whole-number form (2:3), and can also scale a ratio up or down while keeping the same proportion — useful for recipes, mixing ratios, or scaling a design.
How the calculation works
To simplify a ratio, both values are divided by their greatest common divisor (GCD) — the largest number that divides both evenly. To scale a ratio, the same proportion is preserved by multiplying both sides by the same factor.
Formula
Simplified ratio = A ÷ GCD(A, B) : B ÷ GCD(A, B). To scale A:B so that A becomes a new value, multiply B by (new A ÷ original A).
Worked example
The ratio 8:12 simplifies to 2:3 (dividing both by their GCD, 4). Scaled so that the first part is 10, the second part becomes 15, since 10:15 is the same proportion as 2:3.
Understanding your result
The simplified ratio is the smallest whole-number form of your original ratio. The decimal equivalent (A ÷ B) is useful for direct comparisons, like checking whether one mixing ratio is stronger than another.
Factors that affect the result
The result depends only on the two numbers entered. Non-whole-number inputs are supported and simplified proportionally.
Common uses
People use this for scaling recipes, mixing paint or concrete ratios, splitting a bill or profit in a fixed proportion, or solving ratio problems in school.
Important notes
Both values must be zero or positive, and the second value cannot be zero (since a ratio can’t divide by zero).
Frequently asked questions
What is a ratio calculator used for?
It's used to simplify a ratio to its lowest terms, or to scale a ratio proportionally — useful for recipes, mixes, and maths problems.
How do you simplify a ratio?
Divide both numbers by their greatest common divisor (GCD). For example, 8:12 has a GCD of 4, so it simplifies to 2:3.
What does the decimal equivalent mean?
It's simply A divided by B, useful for comparing ratios directly as a single number rather than as two parts.
Can I scale a ratio down as well as up?
Yes — enter any positive value for the new A, larger or smaller than the original, and B will scale proportionally.