While I was an editor at a woodworking magazine, I received a lot of questions about the projects we published. Here are two questions that were tricky to answer:
- How much does that project weigh?
- How much does that project cost to build?
These aren’t really questions that I ask myself as a builder unless I’m making something for NASA or a customer on a crazy tight budget. But readers deserve an answer better than, “I dunno.”
So here’s how to spitball both.
There are lots of published statistics of the average weight of each species. Usually this is listed as the “weight per cubic foot” of that wood. Let’s take koa as an example. A cubic foot of koa is 38 lbs. If you divide that by 12, then you know the weight of one board foot of koa – 3.16 lbs.
Note that this an average weight at an average moisture content.
Here’s a list of species and their weights that I like to use.
Now you need to know how much board footage of wood is in the project. Luckily, there are lots of nice web-based board-footage calculators out there. You simply punch in the dimensions of each part and they spit out how much board footage is in there.
For example, a tabletop that is 3/4” x 26” x 96” is 17.33 board feet.
Here’s a simple board footage calculator that I use.
So if I build that tabletop out of koa, it will weigh 17.33 x 3.16 or 54.88 lbs.
This is tricky, because every lumberyard is different. I can buy ash for $1/board foot. Perhaps you cannot. So I use WoodFinder to look up average prices. Type in the species and it will call up places that carry that species. One of the places I looked at tonight had koa at $36/board foot.
So I can use the board footage calculator to determine that 17.33 board feet of koa will cost me $623.88.
Hmmm. Maybe koa isn’t right for me.
— Christopher Schwarz