Rule of Three Calculator
Solve direct and inverse proportions quickly and accurately.
Si A es a B, entonces C es a X
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Solve direct and inverse proportions quickly and accurately.
Si A es a B, entonces C es a X
Solve direct and inverse proportions with a single tool.
Understand the mathematical process behind each calculation.
From cooking to shopping to construction, proportions are everywhere.
Double-check your manual calculations quickly and accurately.
The rule of three is one of the most practical mathematical tools for everyday life. It solves any problem involving proportional relationships, from scaling a recipe for different servings to calculating fuel needed for a trip.
Understanding proportions is fundamental to many professional fields: engineering uses them for scale drawings, medicine for dosage calculations, finance for currency conversions, and cooking for recipe adjustments.
If more workers means less time, that is inverse proportion. Using direct proportion here gives wrong answers.
The corresponding values must be aligned. Hours with hours, km with km. Mixing units leads to incorrect results.
The rule of three only works when the relationship is truly proportional. Not all real-world relationships are linear.
Always ensure the units in your proportion match. Converting between km and miles, or liters and gallons, before calculating prevents errors.
The rule of three is a mathematical method for solving proportions. If A relates to B as C relates to X, then X = (B x C) / A. It works when two quantities are proportional to each other.
In direct proportion, when one value increases, the other also increases (more hours = more pay). In inverse proportion, when one increases, the other decreases (more workers = less time).
Use it whenever you have a known ratio and need to find a missing value. Common examples: currency conversion, recipe scaling, speed-distance calculations, and unit pricing.
Yes. For example, if 100% corresponds to 250, what does 30% correspond to? X = (250 x 30) / 100 = 75.
Cooking (scaling recipes), shopping (unit prices), travel (fuel consumption), medicine (dosage calculations), and construction (material estimates).