How to calculate percentage between the range of two values a third value is

Question

Example:

I'm trying to figure out the calculation for finding the percentage between two values that a third value is.

Example: The range is 46 to 195. The value 46 would 0%, and the value 195 would be 100% of the range. What percentage of this range is the value 65?

rangeMin=46

rangeMax=195

inputValue=65

inputPercentage = ?

Answer 1

Well, I would use the formula

((input - min) * 100) / (max - min) 

For your example it would be

((65 - 46) * 100) / (195 - 46) = 12.75 

Or a little bit longer

range = max - min correctedStartValue = input - min percentage = (correctedStartValue * 100) / range  

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If you already have the percentage and you're looking for the "input value" in a given range, then you can use the adjusted formula provided by Dustin in the comments:

value = (percentage * (max - min) / 100) + min 

Answer 2

I put together this function to calculate it. It also gives the ability to set a mid way 100% point that then goes back down.

Usage

//[] = optional rangePercentage(input, minimum_range, maximum_normal_range, [maximum_upper_range]);  rangePercentage(250, 0, 500); //returns 50 (as in 50%)  rangePercentage(100, 0, 200, 400); //returns 50 rangePercentage(200, 0, 200, 400); //returns 100  rangePercentage(300, 0, 200, 400); //returns 50  

The function

function rangePercentage (input, range_min, range_max, range_2ndMax){      var percentage = ((input - range_min) * 100) / (range_max - range_min);      if (percentage > 100) {          if (typeof range_2ndMax !== 'undefined'){             percentage = ((range_2ndMax - input) * 100) / (range_2ndMax - range_max);             if (percentage < 0) {                 percentage = 0;             }         } else {             percentage = 100;         }      } else if (percentage < 0){         percentage = 0;     }      return percentage; }