What is roundness?
Roundness is the consistency of the radius along your stroke. A perfectly round circle keeps the same distance from its center at every point. Humans rarely hit mathematical perfection, but your eye is generous—if the radius oscillates only a little, the circle looks convincingly perfect. Our scoring weights roundness highly because the eye notices uneven curvature first.
Variance and why wobble happens
Variance is the average squared difference between your stroke’s radius and the fitted circle’s radius. Large, frequent corrections raise variance and lower roundness. Wrist‑only motion tends to produce linked segments that show up as flat spots. The cure: whole‑arm arcs, relaxed grip, and steady pacing. Switching directions each rep evens out asymmetries baked into your movement pattern.
How we measure roundness (Kasa method)
We fit a circle to your points using the Kasa method, which computes the best‑fit center and radius efficiently. We then compare each sample’s distance from that center to the radius. The more those distances cluster tightly, the higher your roundness score. The method is robust, fast, and correlates well with how people judge circle quality.
Drills to reduce variance
- Tempo Drill (2 min). Draw at 2.5 seconds per circle. Keep pace uniform and avoid micro‑corrections.
- Whole‑Arm Focus (2 min). Lock the wrist and let shoulder + elbow guide the curve. Repeat 10 reps.
- Direction Alternation (2 min). Alternate clockwise and counter‑clockwise every rep to balance bias.
- Size Ladder (2–3 min). Small → medium → large to learn how radius affects control.
Combine these with the exercises from 15 Circle Drawing Exercises and you’ll see roundness climb steadily.
Choosing size and tempo for quality
Most people score best at a medium radius with a calm tempo. If your line jitters, increase the radius slightly and slow to 3 seconds. If the circle looks stiff or segmented, speed up a bit to discourage over‑correction. Always change one variable at a time and compare scores.
Wrap‑up
Roundness is the backbone of a convincing circle. With steady pacing, whole‑arm motion, and a few focused drills, variance shrinks and scores jump. Next, pair roundness control with centering techniques and closure mastery for consistently high results.