Ratio Calculator
Ratio Calculator compares a first value with a second value. It can be read as “A to B” or, when B is nonzero, as the quotient A÷B. A ratio is not automatically reduced to integer terms when inputs are decimals, and the order matters: 2:3 describes a different relationship from 3:2.
Runs locally — files stay on your deviceWhat does a ratio of 2:5 mean?
For every 2 units of the first quantity there are 5 units of the second; A÷B equals 0.4.
A ratio is an ordered multiplicative comparison
A:B compares two quantities. Scaling both by the same nonzero factor produces an equivalent ratio, such as 2:3 and 4:6. The quotient form requires B not to be zero.
How it works
Enter the quantities in the intended order and label their units. Use equivalent-ratio simplification only when it preserves the meaning and useful precision.
Key concepts
Order carries meaning
Teachers:students is not the same label as students:teachers.
Equivalent ratios scale together
Multiplying both terms by the same nonzero value preserves the relationship.
When to use it
- Describe parts, rates, or relative quantities.
- Check the quotient between two numbers.
- Prepare values for an equivalent proportion.
When not to use it
- Do not reverse the order casually.
- Do not divide by a zero second value.
- Do not compare incompatible units without defining a rate.
Worked examples
Simple parts
- Input
2 and 5- Expected output
2:5 and 0.4
The first is forty percent of the second.
Equivalent values
- Input
4 and 6- Expected output
Equivalent to 2:3
Both terms share a factor of two.
Units as a rate
- Input
120 km and 2 h- Expected output
60 km/h after division
Different units create a rate rather than a unitless ratio.
Common mistakes
Reversing terms
The reciprocal relationship is reported. Correction: Write labels in the same order as inputs.
Ignoring units
The quotient can be misdescribed. Correction: Carry units into the interpretation.
Dividing by zero
The quotient is undefined. Correction: Reframe the comparison or use a valid second value.
Best practices
- Label both terms.
- Simplify only when useful.
- Keep enough precision for measured values.
Related operations and differences
Percentage Difference Calculator
Choose Percentage Difference Calculator when you need to compare two values by their average magnitude.; use Ratio Calculator specifically for ratio.
Proportion Calculator
Choose Proportion Calculator when you need to solve A:B = C:X safely.; use Ratio Calculator specifically for ratio.
Average Calculator
Choose Average Calculator when you need to find the arithmetic mean of a number list.; use Ratio Calculator specifically for ratio.
Fraction to Decimal
Choose Fraction to Decimal when you need to convert a numerator and denominator to decimal.; use Ratio Calculator specifically for ratio.
Weighted Average Calculator
Choose Weighted Average Calculator when you need to calculate an average using matching weights.; use Ratio Calculator specifically for ratio.
Percentage Calculator
Choose Percentage Calculator when you need to calculate a percentage of any number.; use Ratio Calculator specifically for ratio.
Limitations and privacy
- Automatic integer simplification may not suit decimal measurements.
- A zero second term has no finite quotient.
- The page does not infer semantic units.
Numbers and results remain in this browser.
Frequently asked questions
Is 2:3 the same as 3:2?
No. They are reciprocals with different order.
Can ratios have units?
Yes; different units form a rate.
What makes ratios equivalent?
Both terms are multiplied or divided by the same nonzero factor.
Can the second value be zero?
The colon notation can be written, but A÷0 has no finite value.