Ring (annulus)
Area and perimeter, with the formula worked through and a drawing to scale.
Result
- Area
- 62.8319 sq ft
- = 62.8319 sq ft · 5.8373 m²
- Perimeter
- 62.8319 ft
- = 62.8319 ft · 19.1511 m
- Outer edge
- 37.6991 ft
- Inner edge
- 25.1327 ft
- Width of the band
- 2 ft
The working
Area: A = π (R² − r²)
Perimeter: P = 2π (R + r) (both edges)
A = π × (6² − 4²) = 62.8319 P = 2π × (6 + 4) = 62.8319
Values in feet; areas in sq ft.
About the ring (annulus)
The band between two circles with the same centre — a path around a round pond, or the wall of a pipe.
Every formula on this site is explained step by step in Learn: area and perimeter.
Other shapes
Square Rectangle Parallelogram Rhombus Trapezoid (trapezium) Kite Triangle — three sides Triangle — base and height Right triangle Isosceles triangle Equilateral triangle Triangle — two sides and the angle between Circle Semicircle Quarter circle Sector (pie slice) Circular segment (arch) Ellipse (oval) Regular polygon (pentagon, hexagon, octagon…) L-shape Any polygon — by corner points