Solve proportion equations (a/b = c/d), scale recipes, and split quantities by ratio. Enter three known values to find the fourth, or divide a total by a given ratio.
This calculator solves direct proportion problems of the form a/b = c/d. You can find any missing value when three are known, or split a total quantity according to a given ratio. Use it for math homework, recipe scaling, financial splits, resource allocation, and more.
For a proportion a/b = c/d, use cross-multiplication: a × d = b × c. If d is unknown, rearrange to d = (b × c) / a. Similarly, c = (a × d) / b, b = (a × d) / c, and a = (b × c) / d.
Add the ratio parts (e.g. 2 + 3 = 5), then divide the total by that sum. Multiply each part of the ratio by this unit value. For 100 split as 2:3, each "unit" is 100/5 = 20, so Part A = 2×20 = 40 and Part B = 3×20 = 60.
Yes. If a recipe serves 4 and you need to serve 10, set up the proportion 4/1 = 10/x for each ingredient, or use the scaling mode to adjust quantities proportionally.
A ratio compares two quantities (e.g. 3:4). A proportion states that two ratios are equal (e.g. 3/4 = 9/12). This calculator handles both: solving proportion equations and splitting totals by ratio.