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Carpentry Formulas

Some useful carpentry maths

This page contains links to some useful carpentry formulas that I'm always using. Maths was never my favourite subject at school (I don't know if it was anyone's) but knowing a few formulas and basic carpentry maths are often helpful in avoiding too much head scratching. I use them to calculate, check for accuracy and for saving lots of time and trouble later on.

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How to check for square 90° corners

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How to bisect an angle

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Calculate how many stair or decking spindles are needed

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How to calculate the square area

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Calcultae the length of a rafter

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Calculate spindle spacings

Carpentry formulas

Carpenters often use formulas and math when carrying out carpentry jobs such as roofing, to check a building is square and to calculate the length of rafters etc.
When designing/building and fitting staircases formulas are used to ensure the treads and risers are the right size and comply with local building codes.
Other carpentry math is used when checking if things like stud walls are perfectly 'square' for example, along with many other day to day carpentry tasks.

Quite often knowing and understanding how to calculate something on paper with a formula will save you the time otherwise spent on trial and error, or finding out later that somethings wrong and having to dismantle, or recut and waste timber. Doing things twice is crap..!

Use the comments box below if there's a formula not included here you'd like to see?

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