Circular Saw Guide: 3 Easy Methods for Straight Cuts

Cutting a straight line through plywood with a circular saw seems like a simple concept, but achieving a perfectly straight cut can be challenging. To improve your results and enhance your woodworking skills, we’ll explore three simple methods to create a guide for your circular saw. In the video above, Jenn Largesse from House One walks through each of these techniques to help you decide which one to use for your next DIY project.

Why Use a Circular Saw Guide?

A circular saw guide is an essential tool for any woodworker or DIY enthusiast. Here’s why using a guide can significantly improve your cutting accuracy:

• Precision: A guide ensures your cuts are straight and true, eliminating wobbles and uneven edges.
• Consistency: With a guide, you can replicate the same cut multiple times with ease.
• Safety: By providing a stable path for your saw, a guide reduces the risk of the blade wandering or binding.
• Efficiency: Once set up, a guide allows you to make quick, accurate cuts without constant measuring and marking.

As Jen from House One explains, getting a straight cut freehand is harder than it seems: “Cutting a straight line with a circular saw seems easy enough, but the line never comes out quite as straight as it feels when you’re making the cut.” That’s exactly why having a reliable guide setup makes all the difference.

Pro Tip: One key challenge when using any straight-edge guide is accounting for the offset—the distance from the saw blade to the edge of the saw’s base plate. As Tommy explains, “if you wanna cut something that’s five inches, you need two measurements: you need the five inches and then you’ve got to adjust” for the offset. Without a purpose-built guide that eliminates this extra step, you’ll need to calculate and mark that offset every single time you set up a cut.

Method 1: Using a Board as a Straightedge

The simplest way to create a guide for your circular saw is by using a straight board clamped to your workpiece. This method is quick and requires minimal setup, making it ideal for occasional use or when working with limited tools. Here are the materials you’ll need:

• Straight board (wider than your saw’s base plate)
• Clamps
• Measuring tape or ruler

Steps to Create and Use a Board Guide

Follow these steps to set up a board guide:

1. Select a straight board that’s wider than your saw’s base plate.
2. Measure and mark your cutting line on the plywood.
3. Position the board on the waste side of your cut line, accounting for the distance between the saw blade and the edge of the base plate.
4. Clamp the board securely to your workpiece and make sure the clamps won’t interfere with the saw’s motor.
5. Double-check your measurements and adjust if necessary.
6. Run your circular saw along the edge of the clamped board to make your cut.

While this method is straightforward, it does have some drawbacks. You’ll need to account for the offset between the blade and the edge of the saw’s base, which can require some trial and error. Additionally, setting up the board for each cut can be time-consuming—especially if you need to make multiple adjustments to get the positioning just right.

Pro Tip: Norm Abram’s solution to the offset hassle is to build a dedicated shooting board from scrap plywood. As he described in This Old House Magazine, start with a piece of half-inch plywood about 7 inches wider than your saw’s sole, then cut a 2-inch strip off the factory edge. Glue and screw that strip back onto the base piece as a fence, then run your saw along the fence to trim the base to the exact width of your saw’s offset. The result is a reusable guide where the edge of the base is your cut line — no offset math required.

Method 2: Creating an L-Shaped Guide

Building upon the first method, this technique adds a perpendicular piece to your straightedge, creating an L-shaped guide. This addition helps square up your cuts more easily and reduces setup time for repeated cuts. This is what you’ll need for this method:

• Straight board (wider than your saw’s base plate)
• Shorter board for the foot
• Wood screws
• Drill
• Measuring tape or ruler
• Clamps

Steps to Create and Use an L-Shaped Guide

Take these steps to use this method:

1. Cut a shorter piece of board to serve as the foot, making it long enough to extend past the edge of your workpiece.
2. Attach the foot perpendicular to the end of your straightedge board. Check that it’s flush and square.
3. Mark your cutting line on the plywood.
4. Position the L-shaped guide on your workpiece, with the foot against the back edge of the plywood.
5. Slide the guide until the straightedge aligns with your cut line, accounting for the saw’s blade offset.
6. Clamp the guide securely to your workpiece.
7. Make your cut by running the saw along the straightedge.

This improved guide saves time by automatically squaring the straightedge to your workpiece, eliminating the need for repeated adjustments. While you may still need to clamp the guide in place, the setup process is much quicker than method one.

Method 3: Creating a Custom Plywood Guide

The third and most versatile method involves creating a custom guide from plywood. This guide allows for cuts on either side of the centerline, making it incredibly useful for a variety of projects. Gather these materials for this method: 

• 1/4-inch thick plywood project panel
• Wood glue
• Circular saw
• Measuring tape or ruler
• Clamps (optional)

Steps to Create and Use a Custom Plywood Guide

Here’s what you need to do to create and use a custom plywood guide:

1. Cut a 4-inch wide strip from the edge of your 1/4-inch plywood panel.
2. Apply wood glue to one side of the strip.
3. Center the strip on the remaining plywood panel and press it down firmly.
4. Allow the glue to dry completely.
5. Once dry, use your circular saw to trim both edges of the glued-on strip, creating perfectly straight edges on both sides of your guide.
6. To use the guide, simply align either edge with your cut line on your workpiece.
7. Make your cut by running the saw along the appropriate edge of the guide.

With this method, there’s no need to measure for blade offset, as the edges are pre-cut to match your saw’s path. You can also make cuts on either side of the guide. You can create a guide of any length for a variety of projects. 

Pro Tip: Norm Abram, master carpenter on This Old House, has long recommended this type of homemade guide—sometimes called a “shooting board”—and finds that a 4-foot length is an especially useful size for crosscutting plywood. For longer rip cuts, you can make the guide up to 8 feet long using scrap plywood.

Tips for Using Circular Saw Guides

To get the most out of your circular saw guide, consider these helpful tips:

• Always ensure your guide is securely clamped or held in place before making a cut.
• Double-check your measurements and guide placement before cutting.
• Use a sharp blade appropriate for the material you’re cutting.
• Support your workpiece properly to prevent sagging or pinching during the cut.
• Practice on scrap material to get comfortable with your guide before tackling important projects.

Pro Tip: In a This Old House episode on making your own circular saw guide, Jen from House One explains the most common pitfall with the clamped-board method: “The key is to use a wide board so that you can keep your clamps clear of the motor of the circular saw. The downside of this method is that you have to take into account the offset of the distance from the blade to the edge of the saw’s base. And it can take a while to set up each time because you may need to make repeated adjustments.”