Cutting accurate circles in wood can be tricky without the right setup. That is why I built this router circle jig — a reusable and adjustable jig that lets me cut clean circles in different sizes without measuring and tracing each one by hand.
I wanted something more versatile than a simple fixed-pivot circle jig. With this version, I can adjust the pivot point, set the circle size precisely, and reuse the same jig for different projects. It takes a little more work to build, but that extra effort makes it much more useful in the workshop.
Another important part of the design was keeping the base as thin as possible. The router sits directly on the jig, so a thinner base leaves more of the router bit available for cutting while still keeping the jig flat and rigid.
There are several ways to cut a circle in wood, but a router is one of my favorite options when I want a smooth, accurate edge. I also have a Universal Router Circle Jig for a different setup, as well as a Table Saw Circle Jig if you prefer working on the table saw.
In this guide, I’ll show you how I built the jig, how the adjustable pivot works, and how I use it to cut accurate circles in wood.
Router Circle Jig Video
If you want to see the complete build before getting started, watch the video below. I show how I make the base, build the adjustable pivot, assemble the jig, and set it up to cut circles with a router.
Seeing the jig in use also makes it easier to understand how the pivot point and measuring scale work together when setting the circle size.
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Table of Contents
- Router Circle Jig Video
- Router Circle Cutting Jig Plans
- Materials and Tools
- Before You Start
- What Is a Router Circle Jig and Why Use One?
- What Router Bit Works Best for Cutting Circles?
- What Router Bit Works Best for Cutting Circles?
- Quick Build Overview
- Step 1: Build the Router Circle Jig Base
- Step 2: Make the Adjustable Pivot and Slider
- Step 3: Assemble the Router Circle Jig
- How to Cut a Circle with a Router Circle Jig
- My Take
- How to Improve the Router Circle Jig
- Woodworking Jigs Used
- Frequently Asked Questions
*Safety is your responsibility. Make sure you know what you’re doing and take all necessary safety precautions while working with power tools. Safety comes first!
Router Circle Jig Plans
You can download the Router Circle Jig Plans below if you want the main dimensions and layout organized in one place while building the jig.
The plans are useful alongside the step-by-step guide below, especially when cutting the base pieces, positioning the router, and setting up the adjustable pivot.
Materials and Tools
Before starting the build, prepare the base materials, pivot hardware, and the basic tools needed for cutting and routing. The jig itself is made mainly from MDF and plywood, with a small brass pin and an M6 bolt forming the adjustable pivot.
Wood / Sheet Material:
- MDF base piece – 515 × 103 × 5 mm finished size
Start with a wider piece, around 515 × 200 mm, and trim it later. - Plywood upper/base piece – 445 × 103 mm finished size
- Plywood slider – 100 × 15 mm
Hardware:
- 1 × M6 bolt, 25 mm
- 1 × T-nut
- 1 × wooden knob or wing nut
- 1 × brass rod, Ø4 mm × 10 mm
- 7 × countersunk wood screws, 10 mm
- Self-adhesive measuring tape
Check all the Tools I Use
Tools:
- Circular Saw – https://amzn.to/4aMD0xg
- Jigsaw – https://amzn.to/3S85cDr
- Trim Router – https://amzn.to/3HbQcOg
- Hand Drill – https://amzn.to/3HqLEnH
- Spring Clamps – https://amzn.to/41Nuh9D
- F-Clamps – https://amzn.to/48ArzY1
- Chisel Set – https://amzn.to/3tHNJrT
Machinist Square / Speed Square
Other:
- Router Bit Set – ø6mm, ø12mm – https://amzn.to/3NQNDVX
- Wood Glue – https://amzn.to/48ltKhJ
- Epoxy – https://amzn.to/3tJ5R4L
- Double-Sided Woodworking Tape – https://amzn.to/3tPMGpM
- Sandpaper Sheets – https://amzn.to/41OMx2p
- Self-adhesive measuring tape – https://amzn.to/3TTjGZb
- 7x Countersunk Wood Screws – 10 mm – https://amzn.to/41PodgQ
We may earn an affiliate commission when you buy something through our retail links. As an Amazon Associate, AllFlavor Workshop earns from qualifying purchases.
Before You Start
What Is a Router Circle Jig and Why Use One?
A router circle jig is a simple guide that lets the router rotate around a fixed pivot point, making it possible to cut accurate circles and arcs in wood. The distance between the router bit and the pivot determines the circle size.
This version is adjustable, so you can move the pivot point along the jig and set different circle sizes without rebuilding the setup each time. That makes it much more useful if you plan to cut circles regularly rather than just once.
How Difficult Is This Router Circle Jig to Build?
This is not the simplest circle jig you can make, but the added complexity gives you much more control. The adjustable pivot, measuring scale, and thin laminated base take a little more time to build, but they make the jig easier to reuse and set accurately later.
I would consider it an intermediate woodworking project. You need a router and basic cutting and drilling tools, but none of the individual steps are especially complicated if you work carefully.
Durable motor delivers the power to meet the toughest applications
What Router Bit Works Best for Cutting Circles?
A straight router bit works well for most circle-cutting jobs, especially if you make several shallow passes instead of trying to cut through the material at once.
A spiral up-cut bit is another good option. It generally gives better chip clearance and maintains more consistent cutting contact, which can help produce a cleaner edge. Router Circle Jig
💡TIP: Whatever bit you use, make multiple shallow passes. It reduces stress on the router and bit and usually gives a cleaner cut.
Smooth and precise cut. Exceptional chip ejection to allow cleaner cutting
Quick Build Overview
Here is a quick overview of the jig before getting into the step-by-step build.
| Item | Details |
|---|---|
| Project | Adjustable router circle jig |
| Main use | Cutting accurate circles and arcs in wood |
| Base material | 5 mm MDF + 6.5 mm plywood |
| Overall jig size | 515 × 103 mm |
| Adjustment | Sliding pivot point with locking knob |
| Pivot | Ø4 mm brass pin |
| Circle range | Approx. 20 mm to 640 mm diameter |
| Router mounting | Router fixed directly to the MDF base |
| Recommended bits | Straight bit or spiral up-cut bit |
| Difficulty | Intermediate |
Let’s Start Building!
This router circle jig is built from two thin base layers that work together to create the adjustable track for the pivot point. The router mounts directly to the MDF base, while the plywood layer helps form the guide slot and keeps the whole jig rigid.
The key part of the design is the sliding pivot pin. By moving it along the jig and locking it in place with the knob, I can change the radius and cut circles in different sizes without building a new jig each time.
I also keep the base as thin as possible so I do not lose too much usable router-bit length. At the same time, it still needs to stay flat and strong enough to handle the pressure of cutting.
NOTE: Router base sizes are different, so use your own router as the reference when laying out the mounting area and adjust the jig dimensions if needed.
How to Make a Router Circle Jig
Step 1: Build the Router Circle Jig Base
The base is made from 5 mm MDF and 6.5 mm plywood. Together, these two layers form the adjustable track for the pivot slider while keeping the jig thin enough to preserve as much usable router-bit length as possible.
1. Cut and Route the Base Pieces
Start with two oversized pieces, around 200 mm wide, and trim them to the final shape later.
Place the router with its original base plate near the end of the MDF piece and mark the width of the router. This gives you the reference for the wider section where the router will eventually be mounted.
Route the main groove along the center of the MDF using a Ø16 mm router bit, leaving about 45 mm at each end. I used a spirit level as a straightedge, but any straight and secure router guide will work.
Next, measure the width of the self-adhesive measuring tape and route a shallow recess beside the main groove. Make it only deep enough for the tape to sit flush with the surface. This side of the MDF will face downward when the jig is assembled.
Repeat the process on the 6.5 mm plywood piece, this time using a Ø6 mm router bit. Leave approximately 50 mm on one side and 40 mm on the other.
💡TIP: Make the grooves as straight and clean as possible. The slider will move inside this track later, so any uneven areas can affect how smoothly the pivot adjustment works.
2. Shape the Base
Temporarily join the MDF and plywood pieces using double-sided woodworking tape. With both layers aligned, draw the final shape of the jig and remove the excess material.
One end of the jig remains wider because this is where the router will sit. I used my Circular Saw Guide Track for the straight cuts.
Separate the two layers again and trim the plywood around the router area. The router attaches only to the MDF layer, so the plywood needs to leave enough clearance around the router base.
3. Attach the Router to the Base
Before working on the router, unplug it or remove the battery.
Remove the original router footplate and use it as a template to transfer the mounting-hole positions onto the MDF base.
Drill the mounting holes and countersink them from the underside so the screw heads sit flush with the bottom of the jig. I reuse the original screws from the router footplate to mount the router directly to the MDF base.
NOTE: Every router base is slightly different. Use your own router and footplate as the template rather than relying only on fixed dimensions.
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Step 2: Make the Adjustable Pivot and Slider
The pivot assembly is what makes this jig adjustable. It slides inside the track and lets you change the distance between the router bit and the pivot point, which sets the radius of the circle.
1. Build the Pivot Slider
Cut the slider to 100 × 15 × 6.5 mm.
Because the MDF base is 5 mm thick, sand the slider until it matches the depth of the track and moves freely without excessive play.
💡TIP: Round the corners of the slider slightly. It helps it move more smoothly inside the track.
Drill a Ø4.2 mm hole near one end for the brass pivot pin and a Ø6 mm hole near the other end for the M6 bolt.
The position of these holes matters because it affects the smallest circle you can cut. In my setup, the pivot pin is about 10 mm from the edge and the bolt is about 20 mm from the opposite end.
2. Install the Pivot Pin and Bolt
Before gluing anything, make sure the bolt head sits flush with or below the bottom of the slider.
You can either carve a recess for the bolt head or drill a larger recess with a Forstner bit and secure the bolt with epoxy. I used the second option because the slider is quite thin.
Insert the Ø4 mm brass rod into the pivot hole and secure it in place. The brass pin should extend enough to locate the center point of the circle without being unnecessarily long.
While the epoxy cures, you can glue the MDF and plywood base pieces together and add screws for extra reinforcement.
NOTE: Keep the underside of the slider as flat as possible. Any proud bolt head or hardened epoxy can stop it from moving smoothly in the track.
3. Make the Locking Knob
I use a wooden knob to lock the slider in position, but a regular wing nut works just as well.
For the wooden knob:
- Mark a circle about 38 mm in diameter.
- Drill six Ø10 mm holes spaced every 60° to create the star shape.
- Drill a Ø6 mm center hole for the bolt.
- Drill a larger recess with a Forstner bit so the T-nut sits flush.
- Cut out the knob with a hole saw. Router Circle Jig
If you make shop knobs regularly, my Star Knob Jig makes this process much faster and more repeatable.
Step 3: Assemble the Router Circle Jig
With the base and adjustable pivot finished, the final step is to put everything together and set up the measuring scale.
1. Install the Pivot Slider
Slide the pivot assembly into the routed track and secure it with the wooden knob or wing nut. The slider should move freely along the track but lock firmly once tightened.
This is the part that lets you adjust the radius of the circle. Move the slider to the required position, tighten the knob, and the pivot point is fixed for the cut.
2. Attach the Router
Mount the router onto the MDF base using the original screws from the router footplate. Make sure everything is tight and that the screw heads on the underside remain flush with the jig surface.
Then install the router bit you plan to use for cutting the circle.
3. Add the Measuring Tape
Stick the self-adhesive measuring tape into the shallow recess routed earlier.
The position of the scale matters. Depending on whether the tape is referenced before or after the router bit, you will be reading either the inner or outer circle dimension. Keep that in mind when setting the size of the circle.
💡TIP: Before relying on the scale, make one test cut and verify the actual circle size. That gives you a chance to fine-tune the zero/reference position of the measuring tape.
Once the slider, router, bit, and measuring tape are installed, the jig is finished and ready to use.
Now the router jig is finished.
How to Cut a Circle With a Router Circle Jig
Once the jig is assembled, setting it up is straightforward. The main things are to secure the workpiece, set the correct radius, and make the cut in several shallow passes.
-
Secure the workpiece
Fix the workpiece firmly to the workbench. I use double-sided woodworking tape, but clamps can work too as long as they do not interfere with the jig. The workpiece should be larger than the final circle. -
Attach the router to the jig
Mount the router securely to the circle jig base with the screws. -
Mark the center point
Determine the center of the circle and make the small hole for the brass pivot pin. -
Set the radius
Slide the pivot to the required position, set the desired radius, and lock it firmly with the knob. -
Choose the router bit
A straight bit works well for most cuts, while a spiral up-cut bit can give better chip clearance and a cleaner edge. For smaller circles, I usually use a 6 mm straight bit. -
Start routing the circle
Place the pivot pin into the center hole, start the router, and slowly rotate the jig around the pivot point. Keep the movement smooth and controlled. -
Make multiple shallow passes
Do not try to cut through the full thickness in one pass. I normally remove around 3 mm of material per pass, clean the groove, lower the bit, and continue until the cut is complete.
💡TIP: Clean the groove between passes. Good chip removal helps reduce heat buildup and usually leaves a cleaner cut.
NOTE: Every material behaves a little differently, so adjust the depth per pass and feed speed as needed rather than forcing the router through the cut.
My Take
I have been using this router circle jig for quite some time now, and I am still happy with how it turned out. It is not the simplest circle jig you can build, but the extra work pays off because the pivot is adjustable and the jig can be reused for circles in different sizes.
What I like most is the combination of accuracy and adjustability. Once the pivot is set and locked, the jig gives me a consistent radius and makes it much easier to cut clean circles than trying to guide the router freehand.
The thin base is another important part of the design. It keeps the router close to the workpiece, so I do not lose too much usable router-bit length, while the MDF and plywood layers still make the jig rigid enough for controlled cuts.
For occasional circle cutting, a simpler jig could be enough. But if you want something you can keep in the workshop and use over and over again, this version is definitely worth the extra effort.
If you want to see more useful workshop builds, take a look at my Best Woodworking Jigs for Your Workshop.
How to Improve the Router Circle Jig
After using this jig for a while, I found a few areas that could make it even more practical.
The biggest limitation of this version is the router attachment. The router is screwed directly to the jig base, which works well, but it takes a little longer to install and remove.
That is one of the reasons I later built my Universal Router Circle Jig. In that version, the router is held in place with a quicker mounting setup instead of being screwed directly to the base.
For occasional use, the screw-mounted version is completely fine. But if you cut circles often, the universal version is faster to set up and more convenient, especially when switching between different routers or using a corded router.
The second improvement would be the pivot system. The current brass pin works well, but it leaves a small hole in the center of the workpiece after the circle is cut. For many projects that does not matter, but for finished surfaces it would be useful to have an alternative setup that does not leave a visible center mark.
So if I were building a second version, I would focus mainly on:
- Faster router attachment
- Easier setup for corded routers
- A pivot option that does not leave a center hole
- Keeping the same adjustable radius system
The current jig already works very well, but these changes would make it even faster to set up and more convenient for frequent use.
Related Router Jigs
If you work with a router regularly, there are a few other jigs that pair well with this build and cover different types of cuts:
- Universal Router Circle Jig – a faster, more flexible option for different routers and frequent circle cutting
- Router Dado Jig – for cutting straight dados, grooves, and rabbets
- Adjustable Router Template Guide – for routing repeatable shapes, openings, and templates
- Adjustable Router Dado Jig – useful when you need to match dado width precisely to the workpiece
These jigs cover different jobs, but they all follow the same idea: making router work more controlled, repeatable, and easier to set up.
Woodworking Jigs Used for This Project
These are some of the workshop jigs I used while building the router circle jig:
- Circular Saw Guide Rail
- Marking Gauge
- Drill Press Table
Not all of them are required, but they make the build easier and help with accurate layout, straight cuts, and drilling.
Frequently Asked Questions
How small of a circle can this router circle jig cut?
With my setup, the smallest circle is around 20 mm in diameter. The exact minimum depends on the position of the pivot pin and how close it can get to the router bit.
How large of a circle can this jig cut?
This version can cut circles up to about 640 mm in diameter. The maximum size is mainly limited by the length of the jig and the available travel of the adjustable pivot.
Can I use a straight router bit to cut circles?
Yes. A straight router bit works well, especially if you make several shallow passes. A spiral up-cut bit is another good option because it improves chip clearance and can leave a cleaner edge.
Why does the pivot pin leave a hole in the center?
This jig uses a physical pivot pin that sits in the center of the circle, so a small hole is left after the cut. For many projects that is not a problem, but if the center must stay untouched, you would need a different pivot setup.
