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

Question

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

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?

valueMin=-46

valueMax=195

valueNow=65

valuePercentage = ?

I have tried the following algorithm but it doesn't work :

const log = (txt) => console.log(txt, 'instead of 100%');

function getValueNowInPercent(valueMin, valueMax, valueNow){
  const diff = valueMax - valueMin;
  const percent = valueNow / diff * 100;  
  return percent + '%';
}

let valueMin, valueMax, valueNow;

valueMin = 0; valueNow = 50; valueMax = 100;
log(getValueNowInPercent(valueMin,valueNow,valueMax));
==> 200% instead of 100%

valueMin = -100; valueNow = 0; valueMax = 100;
log(getValueNowInPercent(valueMin,valueNow,valueMax));
==> 100% instead of 100%

valueMin = 0; valueNow = 100; valueMax = 200;
log(getValueNowInPercent(valueMin,valueNow,valueMax));
==> 200% instead of 100%

valueMin = -200; valueNow = 0; valueMax = 200;
log(getValueNowInPercent(valueMin,valueNow,valueMax));
==> 100% instead of 100%

1 Answers

Vinod Louis · Accepted Answer · 2020-03-20 03:42:59 +0000 UTC

How about mapping this into domain range problem where domain would be your min and max values and range will be from 0 to 100

function mapBetween(currentNum, minAllowed, maxAllowed, min, max) {
  return (maxAllowed - minAllowed) * (currentNum- min) / (max - min) + minAllowed;
}

console.log (mapBetween(-46,0,100,-46,195))
console.log (mapBetween(195,0,100,-46,195))
console.log (mapBetween(65,0,100,-46,195))
console.log (mapBetween(100,0,100,0,200))