Split Value in a Ratio

Name: Split Value in a Ratio
Author: Jürgen Kummer

Calculator to split and round a given value by a specified ratio. A value is divided in such a way that it is set as precisely as possible in the specified ratio. Please enter a value and a ratio (e.g. 1:2 or 3:4). The two parts of the value are calculated and rounded so that the total value remains unchanged.

Examples: Dividing 20 in a one-to-three ratio yields 5 and 15. There is no rounding is required here. However, a value such as 17 should be divided in a 3-to-4 ratio, rounding to three decimal places results in shares of 7.286 and 9.714.

Dividing a value between two recipients according to a specific ratio is a common task and a standard calculation in many applications. The value to be divided is treated as the sum of the two parts of the ratio. A calculation is then performed where the first part is determined by dividing the total value by the sum of the ratio components and multiplying the result by the share of the first part. As in the examples above, 20/4*1, respectively 17/7*3.
Dividing a value according to a ratio often results in fractional numbers. If these are rounded, their sum may not equal the original value. For instance, if both values have a 5 at the rounding position, both would be rounded up, resulting in a total distribution that exceeds the original amount by one, or one tenth or so, according to the rounding position. This issue is resolved here by first calculating the first part of the ratio. The result is then rounded and subtracted from the total to yield the second part. This method works provided the initial total does not have more decimal places than the target rounding precision. It should be insured anyway that the input value has fewer or equal decimal places than the level of precision used. Otherwise, a complete distribution cannot be achieved.

Last updated on 08/29/2026. Author: Jürgen Kummer

Value:
Ratio:	:
Parts:	: