A ratio is a comparison between to values. For example, a solution containing 9 units of salt in 100 units of water has a ratio of 9:100, and a solution of 30 units of alcohol in 100 units of water has an alcohol to water ratio of 30:100. Percentages are also ratios, when the values are expressed out of a total of 100. The term "percent" literally means "per one hundred." Converting from ratio strength to percentage strength is straightforward, but a calculator is required.
Reduce the strength ratio to the lowest common denominator. For example 10:200 can be reduced to 1:20.
Divide 100 by the second number in the ratio. The result is the percentage value of each unit in the solution.
For example the ratio 1:20, contains 20 units. The percentage value of each unit is 100 / 20, or 5.
Multiply the first number in the ratio by the result from Step 2. The result is the strength of the solution expressed as a percentage.
For example, the percentage strength of a 1:20 ratio is 5 per cent because 1 x 5 = 5.
Use an online ratio to percentage calculator to simplify the process. The percentage strength of a solution is the same is the number of grams per 100ml.