This is a handy way of laying out a circle that requires no use of a compass or ruler.
Why bother? Why not just use a compass?
- It’s good practice. Being able to draw a reasonable circle is a handy skill to have for the times when you can’t find a compass.
- Do you struggle with ellipses? If you change the square at the beginning for a rectangle, you can create pretty good ellipses with this method. With some thought, you can even create pretty good ellipses in perspective.
First, start with a square. You can do this pretty well without a ruler, but use one if you have to.
Now sketch in the diagonals.
Now subdivide the square horizontally and vertically. At this point, you have a pretty good idea where the centre of your square is. Now find the distance from the centre to the horizontal or vertical edge. Just use your pencil for this, not a ruler. It’s good practice, remember? This measurement is the radius of your circle.
Now take that measurement and measure it out along each diagonal. Join all the points on your circle and you have an octagon.
Now all you need to do is to draw your circle around the octagon, making sure that the circle goes through all of the points of your octagon.
Here’s a quick video demo of me doing this, so you can see how it’s done.
Obviously, I’ve drawn it much darker that I usually would, using a 6B pencil. Usually, I’d use an H or harder pencil, but the marks wouldn’t show so well on the video!