Board feet decide the price; weight decides whether you can move it and what base it needs. Enter the slab's real dimensions and species and get both, with a proper average for the wavy edge.
The mean solid width along the slab. If the live edge varies a lot, use the Measured widths tab instead.
Measure the solid width at evenly spaced points and the calculator averages them. Leave boxes blank for fewer readings.
Volume in cubic inches is length × average width × thickness. Dividing by 144 gives board feet, the unit slabs are usually priced in; dividing by 1728 gives cubic feet. Weight is the cubic-foot volume times the wood's density, and the calculator reports it in both pounds and kilograms.
A live edge is the whole point of a slab and also the hardest thing to measure, because the width is never constant. Sampling the solid width at several points and averaging is far more accurate than eyeballing a single number, and it is the difference between ordering the right board feet and coming up short.
Density varies widely across species. Purpleheart and hickory are roughly twice as dense as cedar or pine, so two slabs of identical size can differ by a hundred pounds. That is why the weight figure depends on the species you pick, and why a measured density gives the most reliable answer for exotic or unlisted woods.
A large hardwood slab can easily exceed a hundred pounds, which affects how many people you need to move it, whether the top needs support in the middle, and how stout the base or legs must be. Use the weight estimate before you commit to a design, not after the finish is on.