Right scaling solution
======================

As far as I know there is no tool for fitting the created UV layout to the whole square. But you can do this: 
*[In the UV-Editor]*

 1. select all verticies <kbd>A</kbd>
 2. scale your vertecies on the x-Axis by the factor 1.45454545. <kbd>S</kbd> + <kbd>X</kbd> + `1.45454545`
 3. pack the islands <kbd>Ctrl</kbd> + <kbd>P</kbd> (We do this to center the UV-layout. This makes it independent of where your scaling pivot point was)
 4. if you want, you can choose a margin, so that your map isn't exactly in the corners (<kbd>F6</kbd>, then enter something like .333 in the margin field)

Your map should be aligned centered now with no space of the light gray square except the margin left.


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### Why is the factor 1.45454545?

When you look at the screenshot you can count that 5.5 of 8 (large) squares of the x-Axis grid are filled. So $\frac{5.5} 8 = \frac{11}{16}$. If you want to scale them, so they fit 8 of 8 squares, $\frac 8 8 = \frac 1 1 = 1$, you have to multiply by the inverse, namely $(\frac{11}{16})^{-1} = \frac{16}{11} = 1.\overline{45}$, because $\frac{11}{16}\cdot\frac{16}{11} = 1$.