Luma original geometry challenge
Draw a Perfect Circle — Test Your Accuracy Online
Draw with a mouse, pen or finger and see exactly how round, closed and centered your stroke is. Practice freely or complete the deterministic daily shape.
Precision studio
Start drawing
Choose a mode, then draw inside the canvas. · Follow the guide in one steady stroke.
Roundness
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Closure
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Centering
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Local best
0
Daily streak
0
How the score is calculated
For circles, roundness compares every sampled radius, closure measures the first-to-last gap, and centering compares the stroke with the target. Square and triangle use guide match plus closure; the open spiral uses guide match plus endpoint fit. The visible components form the total instead of an unexplained percentage.
Three ways to improve
Start with a comfortable wrist position, keep one steady speed, and aim to meet your starting point without a last-second hook. A larger stroke is usually easier to control than a tiny circle, especially on a phone.
Circle, square, triangle and spiral
Circle is the default challenge. Square, triangle and spiral use shape-specific target geometry, so an open spiral is never penalized for not closing. Shape selection changes only the local guide and formula; it never downloads a level or sends your stroke to a server.
Daily challenge and privacy
The Asia/Shanghai calendar date selects one deterministic daily shape. Best scores and the seven-day streak stay in local browser storage. Sharing creates a short result summary without coordinates, identity, account or device fingerprint.
Perfect Circle FAQ
- Can I draw on a phone?
- Yes. The canvas supports touch, pen and mouse input and fits a 360px viewport without page overflow.
- What affects the score?
- Circle uses roundness, closure and centering. Other shapes use visible guide match plus closure or spiral endpoint fit. No copied or secret competitor formula is used.
- How does the daily challenge work?
- The local calendar date deterministically selects a shape. Replaying the same date does not inflate the streak.
- Is my drawing uploaded?
- No. Practice, scoring, best results and streak calculations happen in this browser; analytics receives only coarse score and input-type buckets.