“Stair angle”, or “pitch”, is the angle at which your stairs descend. This angle is a crucial factor in deciding how to build handrails for your stairs. This article shows you two extremely easy tips for calculating the angle of your stairs!

Included is a short video so you can see the process carried out in step-by-step.



An ANGLE FINDER PROTRACTOR is the quickest way to find stair angles!

A SPEED SQUARE can also play a crucial part…

When paired with a 24″ LEVEL!


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1. Understanding Stair Angle And Handrails

a long set of stairs, leading down from a deck

A long set of stairs, leading down from a deck

Nobody needs an explanation of what stairs and handrails are for. But, it’s important to have a little insight into how stairs and handrails interact with each other.

By code, the tops of handrails must sit 34″-38″ above the nose of any given stair tread. For this reason, it’s absolutely necessary that your handrail follows the exact same pitch as your stairs.

For instance, the handrail pitch may be steeper than your stair angle If so, it will nosedive towards your stairs at the bottom.  Conversely, the handrail pitch may be set shallower than the stair angle. In that case, the handrail gets closer farther from the stairs near the bottom.

Either way, it looks dumb. Not to mention, being out of code compliance!

2. Determine Your Stair Angle

In order to determine your handrail angle, we first determine your stair angle.

Stairs are made up of a series of “rises” and “runs”. The rises are called “risers”; the runs are called “treads. When viewed from the side, the steps create a visual sawtooth. The problem is, it’s hard to read the angle of that sawtoothed structure.

For this reason, we use a tool to help us find the slope of the steps.

We need a straight edge

using a straight edge to find stair pitch angle

Ethan uses a straight edge to find the stair angle.

Really, any reasonably long and straight object works in this application. Above, I use a 2×4 as a “straight edge.” But, first I sight down its edges to make sure it’s actually straight.

Now, confident that the 2×4 is straight, I lay it down along the noses of the stairs.

Typically, there are variations here and there. There are places where the straight edge touches some stairs but not some of the others. That’s okay–we’re really looking for the average angle of the staircase. The 2×4 shows that angle.

Having established this visual line, I can use a few other tools to easily calculate the pitch.

3. Use An Angle Finder To Determine Stair Angle

using swanson angle finder to find stair pitch angle

Ethan uses an angle finder to determine the stair angle.

An “angle finder” is a tool that simply indicates the pitch, or slope, of anything it is resting on. A needle arm swings across a dial face behind a window on the tool. This needle always wants to point directly upward, perpendicular to the horizon. In other words, the needle always wants to be “plumb”.

Set the flat bottom of the angle finder on a flat surface, in this case, your straight edge. The needle points to a degree mark on the face. That number (or tick line between printed numbers) is your stair angle.


That’s it! The angle finder does all the hard work for you. It just needs a flat place to sit, and a moment for the needle to come to rest.

By the way, stairs aren’t the only application where the angle finder comes in handy. It can read the pitch of a roof, slope of a driveway, or angled trim anywhere in your home. Because it’s so universally useful and cheap, I really advise getting one!

But, what if you don’t have an angle finder? The next step shows you how to do the same thing with two more common tools.

4. Using A Level And Speed Square To Find Stair Angle

using a stanley two foot level and speed square to find stair pitch angle

Ethan demontrates another way to determine the stair angle.

A “speed square” is a triangular tool that has about a million uses in carpentry. Here, we use it in conjunction with a 24″ level to calculate our stair angle.

First set one end of your level down on your straight edge. Hold the free end of the level in your hand. Tilt it upward or downward until the spirit bubble is exactly between the two marked lines in the window.

Now, take your speed square and hook the little rail on one of the shorter legs onto your straight edge. Also butt it up to the underside of your spirit level. Rotate the speed square upward until the entire rail is resting against the underside of the level. (This is a lot easier with two people!)

Look closely at your speed square. Printed or engraved marks on the long leg indicate every degree in a 90-degree arc. Whatever mark the top edge of your straight edge is passing through is your stair angle.

This number should be the same, to about a single degree, as your angle finder reading.


masonry stairs with wooden railings at correct stair angle

Here’s a nice set of masonry stairs with wooden railings

You now know the angle at which to set your handrail so that it matches that of your stairs. Use this stair angle number for the miter cuts on the ends of your rails and balusters. You’ll have a railing system that looks even and plumb.


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