DIY Cost Tools
Ratio Calculator
MATH CALCULATOR
Simplify a two-number ratio and convert it to decimal, fractional, percentage, and part-of-total forms.
How it works
The greatest common divisor reduces both integer parts. Additional outputs compare the first value with the second and with their combined total.
Formula
Simplified ratio = (a ÷ gcd) : (b ÷ gcd). Percent comparison = a ÷ b × 100%. Share of total = a ÷ (a + b) × 100%.
Worked example
For 12:18, the greatest common divisor is 6, so the simplified ratio is 2:3. Twelve is 66.67% of eighteen and 40% of their combined total.
Important limits
- This version simplifies whole-number ratios only.
- A share of total is undefined when the two values sum to zero.
- Negative ratios are calculated algebraically and may not suit every real-world interpretation.
Frequently asked questions
Can I simplify three-part ratios?
This calculator handles two values. Reduce multi-part ratios by the common divisor of all parts.
Is 2:3 the same as 2/3?
The quotient is the same comparison, but ratio notation emphasizes two quantities rather than a single fraction.
Sources and review notes
The calculator uses the Euclidean algorithm for the greatest common divisor and standard ratio conversions. Last reviewed September 29, 2026.