Ratio Inputs
Use the mode that matches the comparison or proportion you need to solve.
Solve a : b = c : x.
Ratio Calculator
Simplify ratios, solve proportions, and scale quantities consistently
How It Works
Ratios compare quantities without requiring a shared unit. This calculator reduces ratios, finds a missing proportion value, and scales a recipe or plan by a chosen factor.
Enter positive quantities for the clearest result. Decimal ratios are supported and are reduced using the nearest practical integer form.
- Simplify divides both parts by their greatest common divisor.
- Proportion solving uses cross multiplication: a/b = c/x.
- Scaling multiplies each part of a ratio by the same factor.
- A zero denominator is rejected with an actionable message.
Formulas
Simplified ratio = a / gcd(a, b) : b / gcd(a, b)
Missing value x = (b x c) / a for a:b = c:x
Scaled quantity = original quantity x scale factor
Simplify
24:36
2:3
Both parts divide cleanly by their greatest common divisor.
Proportion
3:5 = 12:x
x = 20
Cross multiplication keeps equivalent ratios balanced.
Recipe scale
2 cups for 5 servings, scaled to 8
3.2 cups
The scale factor applies equally to every quantity.
Can ratios contain decimals?
Yes. Decimal inputs are converted to a practical reduced ratio for display.
What is a proportion?
A proportion states that two ratios are equivalent, such as 3:5 = 12:20.
Can I use a ratio with zero?
A zero part can be meaningful in a simplified comparison, but a zero denominator cannot be used in a proportion calculation.
How is this useful for recipes?
Use Scale mode to multiply every ingredient quantity by the same servings-based factor.