Filament length per print/pound

Is there a way to calculate either length of filament per pound (kilo) or some other way to interpret filament used per project? Repetier gives you a total length after setting up a print, and a cubic amount, but I'm unclear about how that translates to the amount of filament on, say, a 1 pound roll of nylon. It would be good to know for larger projects, or just keeping track of as you go along. Having a multi-hour print stop halfway through, and then be multi-hours more after you got back to it and replenished the filament supply could be avoided.
Maybe someone of you wants to invent a filament length counter as it passes through on its way to the printer?

 

Some guys have worked the maths on this site. Maybe it is of use to you

https://groups.google.com/forum/?fromgroups=#!topic/makerbot/p5roFkXXNHY

 

Thanks, David...

 

so what I am wondering is for thing 25612 that Printed Solid gave a link to, could you just cut the required length of the filament and feed it as it prints OR do you need to create a single length of filament first?

 

For multi-color it appears that either technique is possible. The joined filament is easiest... except you have to join the the filament. There is a great link floating around on making a filament joiner, I saw it yesterday, but I can't remember where it is... sad, eh? I will search for it and post it when I find it.

 

Talking about this one? http://www.thingiverse.com/thing:9850

 

Exactly!