How can I sort individual numbers into groups totalling no more than a specified total?

[mandamoo]

I have a a bunch of lengths that I need to fit into a total lengths of 5000mm.
Is there a way in excel where I can enter lengths and have excell sort them (or optimise them) where they get put into groups that best utilise each 5000mm length?
example: I have the following lengths.... 1350, 1600, 1800, 950, 450, 400, 1800
I need excel to take these numbers and sort them into groups that best use each length of 5000 such as 1800, 1800, 1350 (1st length) and 1600, 950, 450, 500 (2nd length)
Or something similar to this.... can anyone help?
Thanks - Manda