Math for Woodworking, et al

As a woodworker, it is often a regular occurrence to encounter hiccups and hangups when it comes to mathematical equations and calculations. No worries! This is an opportunity to discover new rules and laws of nature when in comes to the physical properties of woodworking. Some are simple, some are complex, but all are necessary and important when it comes to planning the successful completion of any project. I hope you find this article useful for your own projects, even beyond woodworking. Please add you own most-used calculations and what you achieve when you use them.

Radius Equation

Radius Equation

Someone once told me that everything we experience in life can be calculated, in some way or another, by a mathematical equation. I am NOT a mathematician by any means, however, I find it fascinating, intriguing and necessary to learn and experience some of the deeper rules of calculation when it comes to creating and building projects.

Here are a few links and notes that I have encountered along my way in woodworking. I am certain they will come in handy for many.

Arc Finder-

Radius Equation Sketch

Radius Equation Sketch

Find the radius of an arc or segment. I found this when I was researching how to calculate arcs for cabinet doors and other decorative features in my work. Figuring out the equation manually is now my preferred way of doing it.

I posted the equation on the wall in my shop.

Find the Radius of an Arc

Area of a Drum/Cylinder- In the following forum in regards to building a drum sander, calculating the area of the drum is helpful in determining how much sandpaper is needed. In this post, Pat Hawley said, “How much you need depends on the size of the drum you made. You need to calculate the area of the drum and get the same area of velcro. For example: if your drum has a 6″ dia and is 20″ wide then its surface area is 6 X 20 X 3.14 = 376.8 square inches divide the drum surface area by the width of the velcro (say 4″) and you get 376.8/4 = 94.2” length or about 8 feet. In this case I’d get 10 or 11 feet to allow for trimming on the ends.

Find the Area of a Cylinder

Do you use a mathematical equation for your woodworking hobby or business? Please share it here.

Find Radius of an Arc with Construction Master Pro Calculator

Looking at the radius equation sketch shown above, whereas W=CL (chord length) and H=SR (segment rise). Example: CL = 3′ 6″, SR= 1′ 3″



[Clear] [Clear]


3 [Feet] 6 [Inch] [Run]



1 [Feet] 3 [Inch] [Rise]



[Conv] [Arc] (Radius)


1 FEET – 10 3/16 INCH


Arc Angle



Arc Length

4 FEET – 7 1/16 INCH

Press (Arc) more

Various Additional Solutions

Here is another favorite that I use in material estimation, the “T”. Given two numbers, it is easy to find the other.


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