Área Coroa Circular
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
A = π(R²−r²)
About this calculator
The circular ring area calculator determines the region between two concentric circles with radii R (outer) and r (inner). The calculation uses the formula A = π(R² − r²), where π is approximately 3.14159. The result is provided in square units, such as cm² or m², depending on the unit of the radii entered.
How it works: enter the values of the outer radius (R) and inner radius (r) in the designated fields. The tool subtracts the area of the smaller circle from the area of the larger circle, applying the formula automatically. The result is displayed with two decimal places.
When to use: this calculator is useful in engineering, architecture, and design projects involving rings, washers, pipes, or any structure with a circular ring shape. It is also applicable in school geometry problems and material calculations for hollow circular parts.
Cautions: ensure that the radii R and r are in the same unit of measurement to avoid errors. The inner radius r must be smaller than the outer radius R; otherwise, the result will be negative or invalid. For very large or small values, check the input precision.
Frequently asked questions
What is a circular ring?
It is the region between two concentric circles, i.e., circles that share the same center. It looks like a ring.
Can I use this calculator to find the area of a pipe?
Yes, if the pipe has a circular ring cross-section (a hollow cylinder). Simply use the outer and inner radii of the pipe.
What if I swap the radii, entering r larger than R?
The result will be negative, which is not physically meaningful. Always enter the larger radius as R and the smaller as r.
Does the calculator work with any unit of measurement?
Yes, as long as both radii are in the same unit. The result will be in the corresponding square unit.
Do I need to use the exact value of π?
No, the calculator uses π with sufficient precision for common calculations. The result is rounded to two decimal places.