Draw a Perfect Circle
Draw a circle in one continuous stroke — the tool scores how round it is and shows you the perfect circle it should have been.
Everything runs in your browser — nothing you draw is uploaded.
How it works
- Press and hold anywhere on the square canvas, then drag in one continuous motion to trace a circle — with a mouse, trackpad, or your finger on a touchscreen.
- Release to finish the stroke; a score from 0 to 100 animates in, along with a tier comment and a faint ghost overlay of the ideal circle fitted to your line.
- Compare your line to the ghost, watch your session best and attempt history update, then press Try again to beat your score.
Frequently asked questions
- How is the perfect-circle score calculated?
- The tool fits an ideal circle to your stroke by taking the centroid of all your points as the centre and the mean distance from that centre as the radius. It then measures how much each point’s distance deviates from that mean radius, and how far the start and end of your stroke are apart. Low radius variance and a well-closed loop produce a high score; wobble and gaps pull it down.
- Why does it say my line is too short or not a circle?
- Scoring needs a genuine loop, so the stroke must cover a minimum arc length and enclose real area before a score is given. A dot, a short scribble, or a straight line does not sweep enough angle around a centre, so the tool rejects it with a friendly prompt instead of printing a meaningless number. Draw a fuller loop and it will score normally.
- What counts as a good score?
- Most people land between 70 and 90 on their first honest attempt. Breaking 95 by hand is genuinely hard and earns the top tier, while a slow, steady stroke from the elbow rather than the wrist usually beats a fast flick. Scores above 99 typically mean a very small, careful circle where tiny wobbles matter less.
- Is anything I draw sent to a server?
- No. The canvas, the circle fitting, and the scoring all run in JavaScript on your device, and nothing you draw is uploaded or stored anywhere. Your attempt history and session best live only in the page’s memory and vanish when you close or reload the tab.
- Does it work on a phone or tablet?
- Yes. The canvas uses pointer and touch events, so you can draw with a fingertip or a stylus just as well as with a mouse. Touch strokes often score slightly differently because a finger tracks a different path than a cursor, so compare like with like — finger against finger, mouse against mouse.
About this tool
Draw a Perfect Circle is a quick skill game built around one deceptively simple challenge: trace a round circle freehand, in a single unbroken stroke, and see how close to perfect you got. As soon as you lift your finger or release the mouse, the tool scores the stroke from 0 to 100, animates the number into view with a tier comment ranging from “keep practicing” to “inhuman,” and lays a faint ghost of the ideal circle over your line so you can see exactly where you drifted.
The scoring is honest geometry rather than a guess. Every point along your stroke is recorded, and the centre is taken as the average of all those points. The radius is the mean distance from that centre to each point, which defines the ideal circle your hand was aiming for. The tool then looks at two things: how tightly your actual distances cluster around that mean radius — the roundness — and how small the gap is between where you started and where you finished — the closure. A perfectly even radius with the ends meeting up scores near 100; wobble, flat spots, and an open loop each cost points.
A minimum arc length and enclosed area are required before any score appears, which is why a dot or a short line is politely rejected rather than scored. This keeps the game fair and stops trivial marks from gaming a high number. Your best score for the session is tracked at the top, and a short attempt history lets you watch yourself improve across tries without anything being saved beyond the current page.
It works equally well as a five-second distraction, a friendly contest passed around one phone, or a steadiness test for a shaky hand. If you want a better score, slow down and draw from your shoulder or elbow rather than flicking from the wrist, keep a steady pace all the way around instead of rushing the far side, and aim to close the loop cleanly where you began. Everything happens locally in your browser, so there is no upload, no account, and no wait.