PHP calculate percentages

Question

I need some help. It's a simple code, but I don't have idea how to write in down. I have the numbers:

$NumberOne = 500;
$NumberTwo = 430;
$NumberThree = 150;
$NumberFour = 30; 

At all this is:

$Everything = 1110; // all added

Now I want to show what percentage is for example $NumberFour of everything or what percentage is $NumberTwo of $Everything. So the "market share".

Vasili

Have you tried anything? – Backstay

If you find that you're numbering variables, then you should probably be using an array instead – Digitalin

Hint: Percentage is (part/total) * 100. – Sirdar

demo – Digitalin

Answer 1

Use some simple maths: divide the number you wish to find the percentage for by the total and multiply by 100.

Example:

$total = 250;
$portion = 50;
$percentage = ($portion / $total) * 100; // 20

Solution to original example

To get $NumberFour as a percentage of the total amount you'd use:

$percentage = ($NumberFour / $Everything) * 100;

Rounding

Depending on the numbers you're working with, you may want to round the resulting percentage. In my initial example, we get 20% which is a nice round number. The original question however uses 1110 as the total and 30 as the number to calculate the percentage for (2.70270...).

PHP's built in round() function could be useful when working with percentages for display: https://www.php.net/manual/en/function.round.php

echo round($percentage, 2) . '%'; // 2.7% -- (30 / 1110) * 100 rounded to 2dp

Helper Functions

I would only contemplate creating helper functions when their use justifies it (if calculating and displaying a percentage isn't a one-off). I've attached an example below tying together everything from above.

function format_percentage($percentage, $precision = 2) {
    return round($percentage, $precision) . '%';
}

function calculate_percentage($number, $total) {

    // Can't divide by zero so let's catch that early.
    if ($total == 0) {
        return 0;
    }

    return ($number / $total) * 100;
}

function calculate_percentage_for_display($number, $total) {
    return format_percentage(calculate_percentage($number, $total));
}

echo calculate_percentage_for_display(50, 250); // 20%
echo calculate_percentage_for_display(30, 1110); // 2.7%
echo calculate_percentage_for_display(75, 190); // 39.47%

Blindworm

Answer 2

Create function to calculate percentage between two numbers.

<?php

/**
 * Calculate percetage between the numbers
 */

function percentageOf( $number, $everything, $decimals = 2 ){
    return round( $number / $everything * 100, $decimals );
}

$numbers = array( 500, 430, 150, 30 );
$everything = array_sum( $numbers );

echo 'First of everything: '.percentageOf( $numbers[0], $everything )."%\n";
echo 'Second of everything: '.percentageOf( $numbers[1], $everything )."%\n";
echo 'Third of everything: '.percentageOf( $numbers[2], $everything )."%\n";
echo 'Fourth of everything: '.percentageOf( $numbers[3], $everything )."%\n";

?>

This outputs

First of everything: 45.05%
Second of everything: 38.74%
Third of everything: 13.51%
Fourth of everything: 2.7%

Vacate

$numbers = array( 500, 200, 500, 200,100 ); for this array, the total percentage sum is not equal 100, but 99.99 .its always .01 shortage – Airmail

@RockersTechnology It depends. It could be, yes, because it's rounding to two decimals. You can always show more decimals – Vacate

@RockersTechnology yeah, you are basically chopping parts from each calculation using rounding. So, getting 0.01 short is not a problem. – Thickwitted

Answer 3

You can also come up with the percentage with the following formula. For the percentage, add a 0. in front of it. So 5% would be 0.05. Total X 0.05 is the amount.

Fitful

It's same to the answers above. If I want to get 10% of x, I'll multiply it with 0.1. – Thickwitted