Home · Calculators · Ring
Volume tool
Concrete Ring Calculator
The calculator treats a fire pit, a tree ring, or a circular planter wall as a doughnut: the outer circle minus the inner void. Diameters are in feet. Height is in inches. The result is a quantity estimate, not a concrete order.
Your estimate
Assumptions
Volume in cubic feet is π × (outer radius² − inner radius²) × height, with height converted from inches to feet. Cubic yards equal that volume divided by 27. A ring 4 ft outside and 3 ft inside, 12 inches high, is about 5.50 cubic feet, which is 0.20 cubic yards.
Empty fields and values of zero or less are rejected. The inner diameter must be smaller than the outer. This is the concrete in the wall of the ring. It is not the volume of a solid pad, and it is not the dirt you leave in the middle.
A cardboard tube filled solid is a cylinder, not a ring. Use the round calculator in tube mode. A rectangular border around a patio is two or four strips on the curb calculator or the slab tool.