How to Cut Stair Stringers with a Circular Saw

Cutting stair stringers using a circular saw takes good planning, a steady hand and the right tools. This is an important part of building safe, strong and level stairs that may be part of a larger home project. Once you understand how to cut stair stringers, you can justifiably approach a larger home or commercial space build. 

This guide will help you work through the entire step-by-step process, from measuring your rise and run to making a clean cut in the corners to provide the proper cuts your stairs require.

What Are Stair Stringers?

Stair stringers are the angled boards that are used as a base structure for the stairs to hold the steps (treads) and risers in the staircase. They are cut from 2×12 boards, and every cut must be perfect for the stairs in your project to be solid and safe. 

Tools and Materials You’ll Need

• Circular saw (7-1/4″ is ideal)
• Framing square with stair gauges
• Measuring tape
• Pencil or chalk line
• Handsaw or jigsaw
• Clamps
• Safety gear: gloves, goggles, ear plugs

Step by step: How to cut stair stringers

1. Measure total rise and total run

• Start with measuring the total rise, where the total rise is measured as the distance from the lower finished floor to the top landing.
• Divide the total rise measurement by your riser height (7″ to 7.75″) and you will arrive at the quantity of steps that will be needed.
• Use the last number of steps just calculated times your tread depth (typically 10″) in the amount of total run (distance the stairs will stretch out horizontally).

2. Mark the Stair Layout: 

• Using the marking square and your stair gauges, mark the rise and the run on your 2×12. 
• Set the stair gauges for your measurements and then set them on the board (for example, a stair with a 7″ rise and a 10″ run). 
• Place your square at one end of the board and mark your first step. 
• From there, mark down the board in the same manner until you have fully marked out the steps. 

3. Cut your Stringer with a Circular Saw

• With your circular saw, cut along the lines you have drawn. 
• Make sure to not cut all the way through at the inside corners to avoid overcutting. 
• Complete each cut with a handsaw or jigsaw to keep the inner corner clean and the wood strong. 

4. Test fit and copy

• Place your first cut stringer in place to check the fit. 
• If it fits well, trace it and cut the others using it as a template.
• Most stairways need at least 3 stringers, one on either side and one in the middle.

5. Sand and Get Ready for Installation

• Sand all the rough spots and splinters.
• Check all cuts are square and even. For example, check that the “rise” and “run” drawn in actual length equal the same distance from top to bottom. This will help make any adjustment before getting carried away.
• Once everything looks good, you can proceed to install your treads and risers.

Pro Tips

• Use straight, solid 2×12 boards without large knots
• Double-check your measurements before cutting
• Clamp your board so it stays still while cutting
• Label the top and bottom to avoid flipping the board during layout

Why Use a Circular Saw?

A circular saw is great for this job because it cuts clean and fast through thick boards. Just remember that it can’t reach tight inside corners, so you’ll need a handsaw or jigsaw to finish those off neatly.

Safety Tips

• Always wear goggles, gloves, and hearing protection
• Make sure your saw blade is sharp and set at the right depth
• Clamp your board tightly before cutting
• Keep your hands away from the blade path and stay in control of the saw

Common Mistakes to Avoid

• Overcutting inside corners, which weakens the board
• Using twisted or bowed lumber
• Miscounting the number of steps
• Skipping the handsaw finish on corners

Cutting all stringers without testing the first one

When to Use Pre-Made or Metal Stringers

If you’re short on time or working on a bigger project, pre-cut or metal stringers can save you effort. They’re consistent, easy to install, and suitable for commercial or heavy-use stairs.

Final Thoughts

Cutting stair stringers with a circular saw requires time, precision, and a little patience, too. With the right tools and good planning, you can build stairs that are solid, safe, and made to last.

Need the materials or stair products? AAIT has premium materials you can trust, whether it’s a home build or a commercial job.

FAQ’s

Q: Can I use a circular saw to cut stair stringers?

A: You can cut most of it with a circular saw, but you will get a cleaner cut at the corners with a hand or jigsaw.

Q: What size board do I need for stair stringers?

A: A 2×12 is standard because its strength is sufficient to build a supported step that is safe.

Q: How many stringers do I need for stairs?

A: Three is more common. Two on the sides and one in the middle.

Q: Are pre-made stair stringers good for bigger projects?

A: Sure, pre-made stringers are faster and consistent, especially for commercial or high-traffic stairs.