Mr N

Everything I want to remember

Bandwidth Calculator

Posted by on 01 Feb 2008 in Techie

I was looking for an on-line Bandwidth Calculator to find out how many megabytes there were in 100 megabits. Simple I know but hay! I found quite a few, but unfortunately they were all rubbish! I was surprised how many bad implementations there were, some even submitted the form to the remote web server for it to work out. What a waste! Anyway after trawling the wastelands, I decided to write my own.

'B' indicates bytes and 'b' indicates bits so for example, if you want to find out how many megabytes of transfer you can get from a 100 megabit network card then:

  1. Enter 100 in the In unit box.
  2. Select Mb from the In unit drop down.
  3. Select MB from the Out unit drop down.

Unfortunately, I have not figured out how to embed Javascript in a blog page, so here is the Bandwidth Calculator in action. For completeness the code is listed below. 

<html>
<body>

<script language="Javascript">
//<!--
// This code was written by BigSoft Limited.
// Please include this message when you use the code in any form.
// (c) BigSoft Limited 2008
// MIT License
//
function recalc()
{
  var frm = document.forms['converter'];
  var in_val = frm.in.value;
  var in_unit = frm.inunit.options[frm.inunit.selectedIndex].value;
  var out_unit = frm.outunit.options[frm.outunit.selectedIndex].value;

  // convert in to bits
  var bits;
  switch (in_unit)
  {
    case 'b' : bits = in_val                                ; break;
    case 'B' : bits = in_val * 8                            ; break;
    case 'Kb': bits = in_val * 1024                         ; break;
    case 'KB': bits = in_val * 1024 * 8                     ; break;
    case 'Mb': bits = in_val * 1024 * 1024                  ; break;
    case 'MB': bits = in_val * 1024 * 1024 * 8              ; break;
    case 'Gb': bits = in_val * 1024 * 1024 * 1024           ; break;
    case 'GB': bits = in_val * 1024 * 1024 * 1024 * 8       ; break;
    case 'Tb': bits = in_val * 1024 * 1024 * 1024 * 1024    ; break;
    case 'TB': bits = in_val * 1024 * 1024 * 1024 * 1024 * 8; break;
  }

  // convert bits to required unit
  var answer;
  switch (out_unit)
  {
    case 'b' : answer = bits                                ; break;
    case 'B' : answer = bits / 8                            ; break;
    case 'Kb': answer = bits / 1024                         ; break;
    case 'KB': answer = bits / 1024 / 8                     ; break;
    case 'Mb': answer = bits / 1024 / 1024                  ; break;
    case 'MB': answer = bits / 1024 / 1024 / 8              ; break;
    case 'Gb': answer = bits / 1024 / 1024 / 1024           ; break;
    case 'GB': answer = bits / 1024 / 1024 / 1024 / 8       ; break;
    case 'Tb': answer = bits / 1024 / 1024 / 1024 / 1024    ; break;
    case 'TB': answer = bits / 1024 / 1024 / 1024 / 1024 / 8; break;
  }
  frm.out.value = answer;
}
// -->
</script>

<form name="converter">
<table>
<tr>
 <td>In unit</td>
 <td><input name="in" value="0" onChange="recalc();">
<select name="inunit" onChange="recalc()">
<option value="b">b</option>
<option value="B">B</option>
<option value="Kb">Kb</option>
<option value="KB">KB</option>
<option value="Mb">Mb</option>
<option value="MB">MB</option>
<option value="Gb">Gb</option>
<option value="GB">GB</option>
<option value="Tb">Tb</option>
<option value="TB">TB</option>
</select>
</td></tr>
<tr>
 <td>Out unit</td>
 <td><input name="out" value="0"  onFocus="blur();">
<select name="outunit" onChange="recalc();">
<option value="b">b</option>
<option value="B">B</option>
<option value="Kb">Kb</option>
<option value="KB">KB</option>
<option value="Mb">Mb</option>
<option value="MB">MB</option>
<option value="Gb">Gb</option>
<option value="GB">GB</option>
<option value="Tb">Tb</option>
<option value="TB">TB</option>
</select>
</td>
</tr>
</table></form>
</body>
</html>

No feedback yet


Form is loading...