Perfect Circle Test
Usage Tips
Draw slowly in one motion to get closer to a perfect circle
Try drawing a circle without lifting your mouse or finger, and return naturally to the starting point. Keeping a steady speed instead of moving too quickly can help improve your circularity, closure, and smoothness scores.
What is Perfect Circle Test?
Perfect Circle Test is a browser-based circle drawing challenge that scores a mouse or touch stroke by circularity, closure, smoothness, and rotation coverage. It includes an in-canvas score overlay, fullscreen drawing mode, best score, and recent score so users can test roundness, hand steadiness, and drawing accuracy on desktop or mobile.
How to Use
- 1Press on the canvas and draw one circle in a single motion with your mouse or finger.
- 2Use fullscreen mode on small screens when you want a larger drawing area.
- 3Release the stroke to score automatically and view the total score plus circularity, closure, smoothness, and coverage inside the canvas.
- 4Use the retry button in the result overlay to try again and compare the latest score with your best score.
- 5Switch guide modes between blind, center point, and guideline layouts to change the difficulty.
Reference Knowledge
- ●The total score is weighted as circularity 60%, closure 15%, rotation coverage 15%, and smoothness 10%.
- ●Circularity is estimated from how consistent the stroke radius is around the calculated center.
- ●Closure measures the distance between the start and end points, while rotation coverage checks whether the stroke completes a full turn.
- ●Smoothness reflects sudden direction changes, shaky motion, and uneven stroke flow.
- ●Fullscreen mode expands the tool's drawing area inside the page rather than relying on the browser Fullscreen API.
FAQ
Q.How is the perfect circle score calculated?
The score combines circularity, closure, rotation coverage, and smoothness. The current weighting is circularity 60%, closure 15%, rotation coverage 15%, and smoothness 10%, so a high score requires a round, closed, complete, and steady stroke.
Q.Can I use the Perfect Circle Test on mobile?
Yes. The tool supports touch input, so you can draw with a finger on a phone or tablet. If the canvas feels too small, fullscreen mode gives you more room to draw.
Q.When should I use fullscreen mode?
Fullscreen mode is useful on narrow screens or whenever you want a larger drawing surface. It expands the tool area and can be closed with the exit button or Escape key.
Q.Why does an open circle lower the score?
A circle should naturally return close to its starting point. If the start and end points are far apart, the closure score drops because the stroke behaves more like an unfinished loop.
Q.Does hand shake affect the score?
Yes. The smoothness metric detects sudden direction changes and uneven movement, so shaky or jagged strokes can reduce the final score even if the overall shape looks circular.
Q.What do the guide modes do?
Blind mode removes visual help, center point mode keeps only the center reference, and guideline mode shows a clearer circle guide. They are useful for changing difficulty or practicing accuracy.
Q.Is my drawing uploaded to a server?
No. Drawing analysis and scoring run locally in your browser. The tool does not upload your stroke data to a server.