If you need to drill a hole in the center of a circular material, obviously you’ll have to find the center first. You could buy a fancy center-finding tool, alternatively, you can use simple measuring tools and these easy methods to mark the point. Here is how to find the center of a circle using only a ruler or square.

This skill could come in useful in many ways, such as making a perfectly round table! Additionally, if you’re going to do something like that, you will need to not only find the center of a circle but you’ll probably also need to construct a quick DIY router trammel to get some nice finish to that edge.

### How To Find The Center of A Circle With Only A Carpenter Square

#### Step 1:

First, place a carpenter square on the face of the material with the outside corner on the edge of the circle. Trace the outside edge of the square on the circle to draw two perpendicular lines across the circle.

#### Step 2:

Use the straightedge to draw a third line perpendicular to one of the others you had drawn previously. Then, using the square as a straight edge, draw lines from one end of the parallel lines to the opposite end until you have the figure shown above. You have now found the center of the circle with only a carpenter’s square!

TIP: Don’t have a carpenter square? Although you may be missing the nice tool, you can use a piece of paper, book, or anything with a precise right angle to make your marks.

### How To Find The Center of A Circle With A Carpenter Square and Ruler

#### Step 1:

Place a carpenter square on the face of the material with the outside corner on the edge of the circle. Then, lay a ruler across the square where the edges of the square touch the outside edges of the circle. Draw a line along the inside edge of the ruler.

#### Step 2:

Rotate the squares and place them at the edges as you did before, to draw another line. Consequently, you now have an X where you have located the center of the circle.

### How To Find The Center of A Circle With A Carpenter Square and Speed Square

#### Step 1:

Place the inside edges of the carpenter square against the edge of the circle. Place the base of a speed square against the carpenter square and align the angled side with the inside corner of the carpenter square. Draw a line along the angle of the speed square.

#### Step 2:

Rotate the material and repeat Step 1, then draw another line. Finally, you have located the perfect center of a circle using just these tools.