how to set dynamic margin for string length in php

I am trying to set margin for dynamic string length:
My Max String Length is 41.
i am trying code like that but how can it possible for string length 41.
the condition is when count is added in 3 then margin will minus by -5px

      $set_margin_left = '335px'; 
        if(strlen($category['name']) == 3){
           $cal_margin = $set_margin_left;
        }elseif(strlen($category['name']) == 4){
            $cal_margin = '330px'; 
        }elseif(strlen($category['name']) == 5){
            $cal_margin = '325px'; 
        }elseif(strlen($category['name']) == 6){
            $cal_margin = '320px'; 
        }elseif(strlen($category['name']) == 7){
            $cal_margin = '315px'; 
        }elseif(strlen($category['name']) == 8){
            $cal_margin = '310px'; 
        }elseif(strlen($category['name']) == 9){
            $cal_margin = '305px'; 
        }elseif(strlen($category['name']) == 10){
            $cal_margin = '300px'; 
        }elseif(strlen($category['name']) == 11){
            $cal_margin = '295px'; 
        }elseif(strlen($category['name']) == 12){
            $cal_margin = '290px'; 
        }elseif(strlen($category['name']) == 13){
            $cal_margin = '285px'; 
        }elseif(strlen($category['name']) == 14){
            $cal_margin = '280px'; 
        }

>Solution :

A simple mathematic function as you ‘re beginning at 350px that result from 335 + 3 * 5 from your first if condition.

$maxMargin = 350;
$calculatedMargin = $maxMargin - strlen($category) * 5;
$cssValue = $calculatedMargin . 'px';

Assuming that the category string length is 3 the margin would be 335. Assuming the category string length is 14 the margin would be 280 (250 – 5 * 14).