Tip for drawing perfect circles
Published by Manning on July 1st, 2016
A lot of my projects call for drawing various circles to cut out of foam board or poster board. If the exact size isn’t important, I just trace a plate or a bowl or whatever. But sometimes I need a circle to be a precise size, so this is the trick I always use.
I just grab a small rectangular scrap of foam board (or cardboard or poster board) and draw a line on it with a ruler, marking off 0″ and half the size of the circle I want (i.e. the radius of the circle). For this example, I want to make a 10″ circle, so I’ve marked off 5″ on the foam board.
Then I poke a hole in both points with an awl (of course you can use a toothpick, a nail, a sharp pencil, etc). Then I lay this shape onto a big piece of foam board, hold it in place at the 0″ mark with the awl, and put a pen through the 5″ hole, and spin the thing around to draw the 10″ circle. Easy!
(One nice thing about this technique is you already have the exact center of the circle marked. Sometimes that’s important for whatever project you’re doing with the circle. If you start by tracing a plate, it’s really hard to find the exact center from there.)
Of course you can also use a compass for drawing circles, but I actually find that to be much harder to do nicely; there’s something awkward about the twisting motion and having to keep the tip of the pen steady on the paper all the way around. My method is way easier, you can make way bigger circles than with a compass, and I actually think it’s much more accurate than a compass when you’re trying to get a very specific sized circle.
Enjoy!
About Manning Krull
How to make a 4-foot paper maché alligator
My violin skull mask, Mardi Gras 2015
Three-headed paper maché dragon sculpture
July 3rd, 2025 at 3:26 am
This DIY compass method is genius! I love how you can get exact measurements and mark the center at the same time. I totally agree that regular compasses can be awkward to use smoothly. Your foam board technique seems so much more stable. After reading this, I’m curious to test my circle-drawing skills at https://perfect-circle.fun – it’s a fun little game that judges how perfectly round your circles are. Would be interesting to see how different techniques compare!
February 11th, 2026 at 3:38 am
I never thought of using a scrap of foam board as a makeshift compass — that little radius trick sounds way easier than fumbling with a regular compass next time I try a DIY project
March 9th, 2026 at 4:40 pm
The tip about marking the center at 0 and the radius on the same strip makes a lot of sense. I’m curious if you’ve ever had the center pin slip when rotating it, because that’s happened to me a couple times when the paper underneath was thin.
March 14th, 2026 at 7:06 pm
The tip about keeping the pencil perpendicular to the paper caught my attention. I never realized that a slight tilt could make the circle look off, so I’ll definitely try this next time I’m sketchingtitan fishing fish list
April 7th, 2026 at 1:55 am
What a simple but brilliant trick! Circles have always been my weakness.
April 20th, 2026 at 3:17 pm
Thanks for sharing this tip! Drawing perfect circles has always been a challenge for me, and these suggestions are really helpful. I especially like the rotating paper method – will definitely try that!
April 23rd, 2026 at 2:43 pm
I remember struggling to draw precise circles for a Halloween prop last year—this tip would’ve saved me so much time! It’s such a clever hack for DIY projects. Speaking of creativity, I found a similar level of ingenuity in the character routes at Freak Circus, where every choice feels meticulously crafted.
April 26th, 2026 at 11:12 am
The foam board trick for drawing circles is brilliant. I totally agree it’s way easier than using a compass. Imagine trying this while sipping coffee, Free GPT Image 2 generator sounds fun too, doesn’t it? I’m curious how it compares in accuracy.
April 27th, 2026 at 9:09 pm
The radius trick for cutting precise circles is a neat hack—I’ve been using plates for years but didn’t think to measure exactly half the diameter like that. If you’re looking for more DIY project tips like this, I’ve shared similar hands-on ideas over on Gputomine.
May 2nd, 2026 at 6:47 am
I also found Free AI Video really helpful.
May 3rd, 2026 at 4:43 am
This is a great reminder — I’ve also used plates and bowls for rough circles, but the radius method with a foam board scrap is far more precise. Love the simplicity of using just a ruler and a scrap piece.
May 3rd, 2026 at 6:45 am
That radius trick with the scrap board is brilliant—I’d never thought to use the half-length as a compass radius for cutting precise foam circles. Definitely more reliable than tracing random household items when you actually need accuracy.
May 4th, 2026 at 6:21 am
I’m writing the blog comment now. The article describes a DIY method for drawing precise circles on craft boards by using the radius measurement to create a compass-like tool. Here’s the comment: That radius method is a neat trick—I’ve always fudged circle sizes with plates when precision wasn’t critical, but your foam board ruler hack actually solves the problem cleanly. Definitely trying this on my next poster project.
May 8th, 2026 at 2:39 am
This is a clever and practical approach for getting precise circle sizes when working with foam board. Marking half the desired diameter as the radius on a rectangular scrap makes it easy to pivot and trace an exact circle. Definitely going to try this for my own crafts projects.
May 11th, 2026 at 1:29 am
That radius-trick for precise circle cutting is brilliant—using half the diameter as the radius on a straight line is such a simple yet effective workaround for foam board projects. It’s exactly the kind of practical tip that saves time when exact measurements matter but you don’t want to fuss with compasses.
May 14th, 2026 at 5:21 am
I didn’t realize marking half the desired diameter on a scrap board was such an effective workaround for precise circle cutting — definitely going to try this instead of hunting for the right-sized plate next time I’m working with foam board.