Circle Sector Calculator
Calculate sector area, arc length, chord length, and perimeter
About this calculator
The Circle Sector Calculator finds everything about a pie-slice of a circle from its radius and central angle: the arc length rθ, the sector area ½r²θ, the chord that closes the slice, and the sector perimeter 2r + arc. The angle can be entered in degrees or radians and is reported back in both. Radius and angle must be positive. Useful for geometry, machining, and CAD work.
How to use the Circle Sector Calculator calculator
- Enter the measurements you know into the input fields.
- Read the computed properties — they update instantly as you type.
- Compare the diagram with your figure to confirm the setup is right.
- Copy the page URL to share the exact calculation.
Common examples
- r = 6, θ = 60° → arc length 6.283185, sector area 18.849556, chord 6
- r = 10, θ = 90° → arc 15.707963, area 78.539816, chord 14.142136
- r = 4, θ = 1.5 rad → arc 6, area 12, perimeter 14
- r = 10, θ = 90° → sector perimeter 2r + arc = 35.707963
Frequently asked questions
How does the Circle Sector Calculator calculator work?
Enter the known measurements of your figure and the calculator applies the standard geometric formulas to find the remaining properties, alongside a diagram that reflects your numbers. All values are computed with high-precision arithmetic.
When would I use the Circle Sector Calculator calculator?
It helps with geometry homework, technical drawing, construction and DIY layout, and any situation where you know some measurements of a shape and need the rest.
How accurate are the results?
Formulas are evaluated at 30 significant digits of precision internally, including roots and trigonometric functions. Displayed values are rounded for readability, but the underlying computation does not accumulate floating-point drift.
Can I share a specific calculation with someone else?
Yes. Every value you enter updates the URL, so copying the address bar and sharing the link reopens the exact same figure and results for whoever clicks it.