Perfect Circle Game: Draw a Perfect Circle

How to use it: press and hold the left mouse button inside the white box, draw one loop and let go inside the box. Your score appears under the box with a red reference circle. Press Try Again, or just press the mouse button again, for a new attempt.

The Perfect Circle Game asks you to draw a circle freehand with your mouse and then tells you how round it is as a percentage. The game measures every point of your line against the spot where you first pressed the button, so the closer all your points stay to one even distance from that spot, the closer you get to 100%.

That one detail about the starting point changes how you should play, and most people never notice it. The sections below explain exactly how the score is worked out, why a neat circle can still score 80%, and the technique that gets you into the high 90s.

How to play the Perfect Circle Game

Move your mouse pointer into the white box under the title. The pointer turns into a crosshair.
Press and hold the left mouse button. The point where you press becomes the centre the game measures from.
Keep holding the button and draw one loop around that point. A black line follows your pointer.
Release the button inside the white box. The game shows “Your circle is X% perfect!” under the box and draws a red circle on top of your line.
Press Try Again to clear the box, or press the mouse button inside the box to start a fresh attempt straight away.

Each attempt is scored on its own. The game does not keep a best score or a history, so write your best result down if you want to track it.

How the perfect circle score is calculated

The score is an average distance check. When you let go, the game takes every point it recorded along your line and measures how far each one is from the place where you pressed the button. The average of those distances becomes the radius of the red reference circle.

It then works out how far, on average, each point sits from that radius, either inside or outside it. That average error is compared with a fixed scale of 400 pixels (half the width of the drawing box) and turned into a percentage:

An average error of 0 pixels scores 100%.
Every 4 pixels of average error costs 1 percentage point, so an average error of 40 pixels scores 90%.
The score never drops below 0% and is rounded to a whole number.

The red circle is the game showing you its working. It is centred on your starting point and uses your average radius, so wherever your black line drifts outside or inside the red line, that part of the drawing lowered your score.

Why your circle scored lower than it looks

The most common reason is where you started. Most people put the pen down on the edge of the circle and draw around from there, which is how you draw on paper. In this game that makes the starting point the centre, so the distance from it ranges from almost nothing at the start to the full width of the circle on the far side.

We ran mathematically perfect circles through the game’s own formula to show the effect. A flawless circle with a radius of 150 pixels scores only 80% when it starts on its edge, and 99% when the button is pressed at its centre:

Shape drawn (computed with the game’s formula)	Start on the edge	Start at the centre
Perfect circle, radius 50 px	93%	100%
Perfect circle, radius 100 px	87%	99%
Perfect circle, radius 150 px	80%	99%
Perfect circle, radius 200 px	73%	99%

The other reasons are smaller. Pressing the button about 30 pixels away from the true centre costs roughly 5 points at any size, and a slow, shaky line adds many small errors that the average picks up.

How to draw a perfect circle in this game

The best technique is to press in the middle, move out to the edge in one quick stroke, then trace the loop slowly and evenly. Every recorded point counts, so a fast move outwards keeps the few points on that short line from dragging the average down.

Pick a centre point in the white box and press the button there.
Flick straight out to where you want the edge, in one quick movement.
Draw the loop at a steady speed, keeping the same distance from your starting point the whole way round.
Finish back where the loop began and release the button inside the box.
Compare your line with the red circle and see which side you drifted on.

A few habits help with the loop itself:

Move from the elbow or shoulder. Small finger and wrist movements are hard to keep even over a large curve. Resting your forearm on the desk and turning from the elbow gives a smoother arc.
Keep a steady speed. Speeding up on one side of the loop and slowing down on another changes how many points are recorded there, and slow parts tend to wobble.
Lower the pointer speed if it jumps. A very high mouse sensitivity turns a tiny hand tremor into a visible bump. If your line looks jagged, try a slower setting with the help of our guide to mouse pointer speed or check your sensitivity with the mouse DPI analyzer.
Turn off pointer acceleration. With acceleration on, the same hand movement draws a bigger or smaller curve depending on speed, which bends the loop out of shape. Our mouse acceleration guide shows how to switch it off.
Check your grip. A relaxed palm or claw grip is steadier for long curves than a tense fingertip grip. The mouse grip styles guide compares them.

What is a good score?

On this game, 95% or more is a good score and 98% to 100% is excellent, provided you started at the centre. If you start on the edge, even a perfect shape is capped well below that, so a score in the 80s from an edge start is a sign of a very round circle.

Keep in mind what the score does and does not measure. It only checks that your points keep an even distance from the starting point. It does not check smoothness, speed or whether the loop is closed, and it is generous with shapes that are not circles at all:

Shape drawn from its centre (radius or half width 150 px)	Score
Perfect circle	99%
Circle with a wobble of 10% in its radius	97%
Oval three quarters as tall as it is wide	97%
Square	96%

So treat a high score as a sign of a steady, even hand rather than a certificate of a flawless circle. The red reference circle is a better judge: if your black line hides under it all the way round, the circle really is close to perfect.

Does the size of the circle matter?

Yes. The error is counted in pixels, not as a share of the radius, so the same wobble costs fewer points on a small circle than on a large one. Comparing scores is only fair when both people draw circles of a similar size.

Can a human draw a perfect circle?

No hand-drawn circle is mathematically perfect, because a perfect circle has every point at exactly the same distance from the centre and any real line has some wobble. People can get very close, though, and freehand circles have a long history as a test of skill.

The best-known story comes from Giorgio Vasari’s Lives of the Artists. A courtier sent by Pope Benedict asked the painter Giotto for a drawing to show his skill. Giotto dipped a pen in red and, with his arm fixed against his side like a compass, drew a circle with one turn of his hand. The story comes only from Vasari and is not independently confirmed, but it gave Tuscany the teasing saying “rounder than Giotto’s O” for a slow-witted person.

In 2007 a video of Alexander Overwijk drawing a large chalk circle on a blackboard spread widely online, linked to a freehand circle drawing championship he won that year. A 2018 analysis of a frame from the video fitted a perfect circle to his drawing and divided the area of his shape by the area of the fitted circle, a stricter method than this game uses. The result was 0.997, where 1 would be perfect. No official record body tracks freehand circles, so treat any “world record” score you see online with care.

Phones, tablets and screen size

The Perfect Circle Game reads mouse movements only. On a phone or tablet, dragging a finger across the box does not draw a line, so play it on a computer with a mouse or a trackpad. A trackpad works, but holding the click while you trace a loop is harder than with a mouse, so expect lower scores.

Use a browser window wide enough to show the whole white box. If the window is narrower than the box, the box shrinks to fit and the line can drift away from your pointer, which makes the result meaningless. Releasing the button outside the box does not end the attempt; move back into the box and release there to get your score.

More games and mouse tests on Click Tester

If you enjoy testing how steady and accurate your hand is, these work the same skills in different ways:

Aim Trainer: click targets as they appear to test speed and precision together.
Mouse accuracy guide: practical ways to make your pointer movement more precise.
Coreball Game: a timing game where every pin has to land in a gap.
Reaction Time Test: measure how quickly you respond to a colour change.
Clicker games: all the click speed games on the site in one place.
Mouse Test: check that every mouse button and the scroll wheel work properly.

Frequently asked questions

How do you get 100% in the Perfect Circle Game?

Press the mouse button at the centre of your planned circle, move out to the edge quickly and trace a steady loop at the same distance all the way round. A small, even circle drawn this way can round up to 100%. Starting on the edge of the circle makes 100% impossible, because the distance from the start changes all the way round.

What is a good score in the Perfect Circle Game?

A score of 95% or more is good and 98% or more is excellent when you start in the centre. From an edge start, a score in the 80s already means a very round circle. Scores are only comparable between circles of a similar size.

Why is my perfect circle score so low?

You probably started drawing on the edge of the circle. The game measures from the point where you pressed the button, so starting on the edge can cost 20 points or more even for a neat circle. Start in the middle and move outwards first.

What does the red circle mean?

The red circle is the reference the game compared your line with. It is centred where you pressed the button and uses the average distance of your line from that point as its radius. Any part of your line well away from the red circle lowered your score.

Can I play the Perfect Circle Game on a phone?

Not at the moment. The game only listens for mouse input, so dragging a finger on a touch screen does not draw. Use a computer with a mouse or a trackpad.

Is my score saved?

No. Each attempt is scored on its own and the game does not store results, keep a best score or send your drawing anywhere. Note your score down if you want to compare later.

Can anyone draw a perfectly round circle by hand?

Not a mathematically perfect one, since every hand-drawn line has some wobble. Skilled people get very close, and the story of Giotto’s freehand circle has been told for centuries as proof of an artist’s control.