# How do I calculate the size of padded envelope needed for a given size box?

When you put a box of dimensions (W x H X D) in a padded envelope of dimensions (X x Y), what is the mathematics?

The padded envelope also has to have a flap of length (F), it also has welded seams (S). There also needs to be some extra gap so the box can be taken in/out (G). The corners are tricky because of how the paper creases - this takes the maths out of basic trigonometry. For this reason I would like a bit of help with my homework!

-
Don't you just need $X \geq H+W$ and $Y \geq H+D$? – gfes Jun 4 '11 at 23:14
...pretty much, however the envelope is a custom size and I therefore need the ideal dimensions. Thanks for your insight as I had not thought about finding the next up standard size and that is a good idea. – Mathew Jun 4 '11 at 23:52