Sector Area Calculator

Calculate the area of a circular sector from radius and angle, diameter and angle, arc length and radius, or a fraction of a circle. Estimate square feet, square inches, square yards, square meters, arc length, chord length, perimeter, waste, material quantity, and cost.

Calculate Sector Area

Sector Area = (Angle ÷ 360) × π × Radius². Arc Length = (Angle ÷ 360) × 2π × Radius.
Your result will appear here.

How the sector area calculator works

Radius and angle mode:
The calculator finds the full circle area, then multiplies by the angle divided by 360.

Diameter and angle mode:
The calculator divides the diameter by 2 to get the radius, then calculates the sector area.

Arc length and radius mode:
The calculator estimates sector area using arc length and radius, then calculates the central angle.

Fraction mode:
The calculator uses the percent of a circle to estimate sector area, angle, arc length, and perimeter.

Why use a sector area calculator?

A sector area calculator helps estimate wedge-shaped circular spaces for patios, pools, garden beds, fire pits, paver designs, landscaping, and construction layouts.

It can help calculate square footage, compare area units, estimate arc length, estimate material quantity, add waste, and estimate project cost.

What your result means

Your result shows the sector area, central angle, radius, diameter, arc length, chord length, sector perimeter, area with extra waste, estimated pieces or units needed, and estimated cost.

Sector area formulas

Frequently asked questions

How do I calculate the area of a sector?

Divide the central angle by 360, then multiply by the full circle area. The formula is Sector Area = (Angle ÷ 360) × π × Radius².

What is a sector of a circle?

A sector is a wedge-shaped part of a circle formed by two radii and the arc between them.

How do I calculate sector area from arc length?

Multiply the radius by the arc length, then divide by 2. The formula is Sector Area = 1/2 × Radius × Arc Length.

How do I calculate the perimeter of a sector?

Add the two radius sides and the arc length. The formula is Sector Perimeter = 2 × Radius + Arc Length.

Should I add waste for sector-shaped materials?

Yes. Curved and wedge-shaped layouts often create cuts and offcuts. For pavers, sod, landscaping fabric, tile, concrete, mulch fabric, or flooring, adding 5% to 15% extra is commonly helpful.