How to Draw a Perfect Circle Using a Pin

Co-authored by Kyle Hall Reviewed by Kelly Medford

Last Updated: September 30, 2022

Drawing a perfect circle freehand can be difficult and frustrating. While it’s easy to draw a perfect circle with a compass or a protractor , there’s still hope if you don’t have these tools on hand. With just a pin and some string, you can easily sketch a circle that is nice and symmetrical.

Part 1

Part 1 of 2:

Setting up the Pin and String

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1
Cut string that’s 1–2 inches (2.5–5.1 cm) longer than your desired radius. The circle you draw will have a diameter that's twice as long as the string you use, but you should cut it 1–2 inches (2.5–5.1 cm) longer than you want at first since you'll lose some of the length when you tie a loop at each end. ^{[1]
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- For example, if you want your circle to be 4 inches (10 cm) across, then your desired radius would be 2 inches (5.1 cm) since the radius is equal to half of the diameter. Therefore, you’d cut the piece of string to be about 3–4 inches (7.6–10.2 cm) long so you have extra string on each end to tie the loops with.
2
Tie a small loop at each end of the string. You’ll use one of the loops to attach the string to a pin and the other loop to attach it to a pencil. The size of the loops doesn’t need to be precise, but make sure they’re big enough to fit around a pencil and pin but not so big that they use up a lot of the string that you cut. ^{[2]
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- When you’re finished tying the loops, you can measure the length of the string to determine what the exact radius of your circle will be. If the radius is too short, you can always cut a longer piece of string and try again.
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3
Place a piece of paper over some cardboard, styrofoam, or cork board. Any kind of material will work as long as you’re able to press a pin into it. This base under the paper will give the pin something to stick into and help hold it in place as you use it to draw your circle.
- If you’re drawing your circle onto a piece of thick material, like foam poster board or canvas, you can skip this step.
- If you don’t have anything to use as a base under your sheet of paper, you can try holding the pin in place on the paper with your fingers instead.
Any kind of push pin will work, although the shorter the pin, the easier it will be to work with (since a tall pin might stick up more and be less stable). Make sure it’s not too close to the edge of the paper or else your circle might go off the page when you draw it. ^{[3]
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5
Loop one end of the string over the pin. Don’t worry about tightening the loop. As long as it’s wrapped around the pin, you’re all set. ^{[4]
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- It doesn’t matter what end of the string you wrap around the pin. Just make sure the loop on the other end is big enough to wrap around a pencil.