Ratio Calculator - Calculate Ratios, Proportions & Cross Multiply
Result:
3/4 = 6/x = 8
x = (4 × 6) ÷ 3 = 8
How Ratio Calculation Works
Input Values
Enter known ratio values
Select Type
Choose calculation method
Calculate
Apply ratio formulas
Ratio Formulas & Calculations
Cross Multiplication
Used to solve proportions by multiplying diagonally
Ratio Simplification
Divide both terms by their Greatest Common Divisor
Percentage Ratio
Convert ratio to percentage form
Decimal Ratio
Express ratio as decimal number
Common Ratios Conversion Table
| Ratio | Decimal | Percentage | Fraction |
|---|---|---|---|
| 1:1 | 1.000 | 100% | 1/1 |
| 1:2 | 0.500 | 50% | 1/2 |
| 1:3 | 0.333 | 33.33% | 1/3 |
| 1:4 | 0.250 | 25% | 1/4 |
| 2:3 | 0.667 | 66.67% | 2/3 |
| 3:4 | 0.750 | 75% | 3/4 |
| 2:5 | 0.400 | 40% | 2/5 |
| 3:5 | 0.600 | 60% | 3/5 |
| 4:5 | 0.800 | 80% | 4/5 |
| 5:6 | 0.833 | 83.33% | 5/6 |
| 7:8 | 0.875 | 87.5% | 7/8 |
| 9:10 | 0.900 | 90% | 9/10 |
| 1:10 | 0.100 | 10% | 1/10 |
| 3:10 | 0.300 | 30% | 3/10 |
| 7:10 | 0.700 | 70% | 7/10 |
Ratio Progression Chart
Practice Problems
Problem 1:
If 3:4 = 9:x, find x
Solution: 3x = 4×9, x = 36÷3 = 12
Problem 2:
Simplify the ratio 24:36
Solution: GCD(24,36) = 12, so 24:36 = 2:3
Problem 3:
Convert 5:8 to percentage
Solution: (5÷8)×100 = 62.5%
Problem 4:
If 2:5 = x:15, find x
Solution: 5x = 2×15, x = 30÷5 = 6
Problem 5:
Express 0.75 as a ratio
Solution: 0.75 = 75/100 = 3:4
Daily Uses of Ratios
Recipe scaling uses ratios to adjust ingredient quantities
Map scales show distance ratios between reality and paper
Financial ratios analyze company performance and health
Gear ratios determine mechanical advantage in machines
Aspect ratios define screen and image proportions
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Dr. Jane Doe
VerifiedExpert Reviewer & Mathematician
Last Updated: May 19, 2026