Proportion Calculator

A proportion is a mathematical statement that two ratios are equal. It is written in the form A/B = C/D, meaning that A relates to B in the same way that C relates to D. The symbol '::' is also used to express proportions, as in A : B :: C : D.

To solve a proportion, use cross-multiplication. Multiply the numerator of one fraction by the denominator of the other and set the two products equal. For example, in A/B = C/D, multiply A × D and B × C, then isolate the unknown variable by dividing both sides by its coefficient.

Enter three known numbers into the fields A, B, C, and D, and type 'x' in the field representing the unknown value. The calculator will apply cross-multiplication automatically and display the solved value of x along with both cross products.

Cross products are obtained by multiplying diagonally across the equal sign in a proportion. In A/B = C/D, the cross products are A × D and B × C. If the proportion is valid (i.e., the ratios are truly equal), these two cross products will always be equal to each other.

Yes. You can place 'x' in any one of the four positions — A, B, C, or D — and enter known numbers in the other three fields. The calculator will solve for x regardless of which position it occupies.

The constant of proportionality (often written as k) is the ratio that relates two proportional quantities. In a direct proportion y = kx, k equals y divided by x and remains the same for all corresponding values of x and y.

A ratio compares two quantities, such as 2:5. A proportion states that two ratios are equal, such as 2/5 = 4/10. In short, a proportion is an equation made up of two equal ratios.

Absolutely. Proportions appear in everyday situations like scaling recipes, converting units, calculating discounts, map reading, mixing solutions, and determining tax amounts. Any time two quantities maintain a constant ratio, you are working with a proportional relationship.