Handy dandy for sure. I like the log calculator too, and wonder how that one works. I've used the formula for finding cylinder volume as a guess-timate for the cubic feet in a log..., which will obviously be less than when it's split and stacked with all the air space.
Firewood & Cord Calcuations
How to figure out how much wood you've got!
A cord of firewood measures 4' x 4' x 8' and contains 128 cubic feet. You can calculate the size of a stack in cubic feet by measuring the height, depth, and length of the stack and multiplying one by the other two. For instance: