Circle Calculator
Calculate circle area, radius, circumference, and diameter.
Quadratic Equation Solver (ax² + bx + c = 0)
About Circle Calculator
The Comprehensive Circle Geometry Calculator computes Radius ($r$), Diameter ($d = 2r$), Circumference ($C = 2\pi r$), Surface Area ($A = \pi r^2$), Circular Sector Area, Arc Length, Chord Length, and Circle Equation ($(x-h)^2 + (y-k)^2 = r^2$) from any single known property.
How to Use Circle Calculator
Step 1
Enter any one known property (Radius, Diameter, Circumference, or Area).
Step 2
Optionally specify a central sector angle in degrees.
Step 3
Review computed circle radius, diameter, area, circumference, and arc properties.
Step 4
Click "Copy Circle Specs".
Practical Use Cases for Circle Calculator
Landscaping & Round Table Top Material Calculations
Calculate square footage area and perimeter border edging required for circular garden beds and round patio pavers.
Mechanical Pipe, Pulley & Gear Engineering
Compute outer circular circumference and rotational cross-sectional flow area for fluid piping and drive pulleys.
Input & Output Examples
Calculating Circle Properties from Circumference = 31.4159
Circumference (C): `31.4159`
Radius: `5.0` | Diameter: `10.0` | Area: `78.5398` (Exact: `25π`) | Sector Area (60°): `13.09` | Arc Length (60°): `5.236`
Key Features & Performance
- ✓Instant Multi-Property Solver: enter any ONE property (Radius, Diameter, Circumference, or Area) and all other values are computed instantly.
- ✓Exact Pi Notation: outputs both exact multiples of $\pi$ (e.g. $25\pi$) and high-precision decimal evaluations.
- ✓Circular Sector & Segment Mode: computes Arc Length ($s = r\theta$), Sector Area, and Chord Length for any central angle $\theta$.
- ✓100% Client-Side geometry engine.
- ✓1-Click Copy circle specifications.
Key Terminology & Definitions
Circumference ($C$)
The linear distance around the outer boundary of a circle, calculated as $C = 2\pi r = \pi d$.
Circular Sector
The portion of a disk enclosed by two radii and an arc (resembling a pizza slice), with area $A = \frac{1}{2} r^2 \theta$.