Margin Calculator

calculate-margins.js

// MARGIN CALCULATOR
// source: https://goo.gl/D3k5Fz
/* here's some javascript, courtesy John Smith, to calculate the margins */

var width = 5.5;
var height = 8.5; 


// and here are all the paper sizes you could ever need 
// as inputs to the script above to calculate the margins: 
// https://en.wikipedia.org/wiki/Paper_size

/* y = mx + b (b = 0) */ 
var slope = height / width;

/* (x-a)^2 + (y-b)^2 = r^2 */ 
var radius = width / 2; 
var a = radius; 
var b = height - radius;

/* ex^2 + fx + g = 0 */ 
var e = (1 + Math.pow(slope, 2)); 
var f = (2 * slope * (-b) - 2 * a); 
var g = Math.pow(a, 2) + Math.pow(-b, 2) - Math.pow(radius, 2);

/* x1 = (-f + sqrt(f^2 - 4eg)) / 2e */ 
var x1 = (-f + Math.sqrt(Math.pow(f, 2) - (4 * e * g))) / (2 * e);

/* x1 = (-f - sqrt(f^2 - 4eg)) / 2e */ 
var x2 = (-f - Math.sqrt(Math.pow(f, 2) - (4 * e * g))) / (2 * e);

/* y1 = mx1 + b (b = 0) */ 
var y1 = slope * x1;

document.write('height: ' + height + ''); 
document.write('width: ' + width + ''); 
document.write('slope: ' + slope + ''); 
document.write('radius: ' + radius + ''); 
document.write('a: ' + a + ''); 
document.write('b: ' + b + ''); 
document.write('e: ' + e + ''); 
document.write('f: ' + f + ''); 
document.write('g: ' + g + ''); 
document.write('x1: ' + x1 + ''); 
document.write('x2: ' + x2 + ''); 
document.write('y1: ' + y1 + ''); 
document.write('top and bottom margin: ' + (height - y1) + ''); 
document.write('left and right margin: ' + (width - x1) + '');