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Results
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About the Circle from 3 Points
The circle from 3 points is a free online tool: centre, radius and equation through three points. Enter x₁, y₁, x₂, y₂, x₃ and y₃ and the results update instantly, alongside a labelled diagram so you always know which measurement goes where.
It runs entirely in your browser, so nothing you type is uploaded or stored. Use the share button to copy a link that restores your exact inputs.
Circle from 3 Points example
x₁ = 0 cm
y₁ = 5 cm
x₂ = 5 cm
y₂ = 0 cm
x₃ = 0 cm
y₃ = -5 cmRadius = 5 cm
Centre = (0, 0)
Equation = x² + y² = 25
Diameter = 10 cm
Circumference = 31.4159 cm
Area = 78.5398 cm²How to use the Circle from 3 Points
- Pick the unit your measurements use. All dimensions must share the same unit.
- Enter x₁, y₁, x₂, y₂, x₃ and y₃. Focus a field to highlight the matching label on the diagram.
- Read the results as you type. The largest card is the main answer; the others are the related measurements.
- Copy a single value, copy everything, or share a link that keeps your inputs.
Circle from 3 Points FAQ
What formulas does the circle from 3 points use?
(x − h)² + (y − k)² = r²; Centre from perpendicular bisectors; r = distance(centre, any point).
Why is there no circle for some points?
Three points on one straight line (collinear) never lie on a common circle.
Can I use different units?
Yes. Pick the input unit and, if you like, a different output unit. Area results are shown in squared units and volumes in cubed units.
Is this circle from 3 points free and private?
Yes. It is free with no sign-up, and calculations happen on your device, so your numbers are never sent to a server.
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