Circle Sector, Segment,
Chord and Arc Calculator

Scroll to the bottom for the Circle Calculator
Click here for the formulas used in this calculator.

Lines AO and OB are called radii.
Lines AC, BC and AB are called chords.
The angle ACB is an inscribed angle.
The angle AOB is a central angle.
The curved line AB is called an arc.
Line OE is the apothem and is the height of triangle AOB.
Line ED is the segment height or the sagitta - a rarely-used term.




The length of an arc equals (Central Angle / 180°) • π • r
The yellow area that resembles a "pizza slice" is a sector.
The area of a sector equals (Angle AOB / 360°) •π • r²

The green area (Circle Two) is a segment.
The area of a segment equals
Sector Area Minus Triangle AOB Area

Circle Calculator

Click on the 2 variables you know



Radius and Central Angle    Radius & Chord
Radius & Segment Height     Radius & Apothem


Chord & Segment Height      Chord & Apothem
Segment Height & Apothem
Chord & Arc














Significant Figures >>>
Numbers are displayed in scientific notation in the amount of significant figures you specify. For easier readability, numbers between 1,000 and -1,000 will not be in scientific notation but will still have the same precision.
You may change the number of significant figures displayed by changing the number in the box above.
Most browsers, will display the answers properly but if you are seeing no answers at all, enter a zero in the box above, which will eliminate all formatting but at least you will see the answers.


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