Use the attribute text-anchor="middle" instead of computing the width yourself (which is hard to do as you usually wouldn't easily get at the individual glyphs' widths of the particular font being used).

Here's an example that centers text above a rectangle: 

<?xml version="1.0" encoding="UTF-8"?>
<svg version="1.2" width="100%" height="100%" viewBox="0 0 1000 1000"
    xmlns="http://www.w3.org/2000/svg">

 <g transform="translate(100 100)">
   <rect width="200" height="50" x="-100" y="10" fill="lightyellow"/>
   <text text-anchor="middle">Some centered text</text>
 </g>
</svg>

[download]

(tested with Firefox 3.6.8 and Opera 10.63)

In reply to Re: SVG text width calculation by Anonyrnous Monk
in thread SVG text width calculation by Anonymous Monk

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