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Annulus (ring) area calculator

Compute the area of a ring from its outer and inner radius.

Related tools

All Geometry tools →
Area calculatorCompute the area of a rectangle, square, circle or triangle.Circle sector area calculatorCompute the area and arc length of a circle sector from its radius and angle.Cone surface area calculatorCompute the total surface area and slant height of a cone from its radius and height.Ellipse area calculatorCompute the area of an ellipse from its semi-major and semi-minor axes.Triangle area calculator (Heron's formula)Compute a triangle's area from the length of its three sides.Hexagon area calculatorCompute the area of a regular hexagon from its side length.Parallelogram area calculatorCompute the area of a parallelogram from its base and height.Rhombus area calculatorCompute the area of a rhombus from its two diagonals.

The Annulus (ring) area calculator turns Outer radius, Inner radius into Area, instantly and for free. For instance, with Outer radius = 10 and Inner radius = 6 it returns Area = 201.062.

How to use it

  1. Enter your values: Outer radius, Inner radius.
  2. Read the result instantly: Area.

Frequently asked questions

What does the Annulus (ring) area calculator actually compute?

It takes Outer radius and Inner radius and derives Area from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

2 values: Outer radius and Inner radius. Nothing else is required — no account, no file upload.

Can you show a worked example?

With Outer radius = 10 and Inner radius = 6, the calculator returns Area = 201.062. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Outer radius = 20 and Inner radius = 12 instead, Area goes from 201.062 to 804.248 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Outer radius = 5 and Inner radius = 3, Area comes out at 50.266. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Homework and site work alike: how much paint a wall takes, how much water a tank holds, whether a corner is square — and, on the coordinate side, the slope between two points, the distance across a plan, the midpoint of a span.

What is the most common mistake?

Mixing units inside one shape. Entering a length in centimetres and a width in metres gives an area wrong by a factor of a hundred, and the result looks perfectly plausible.

What is the difference between the Annulus (ring) area calculator and the Area calculator?

Both return Area. What differs is what they ask for: this one wants Outer radius and Inner radius, the Area calculator wants Shape and Dimension 1 (width / radius / base). Use whichever matches the numbers you already have.

Is there a tool for the next step?

Circle sector area calculator is the closest one after this: Compute the area and arc length of a circle sector from its radius and angle.

What else is worth having open alongside it?

Cone surface area calculator and Ellipse area calculator — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
How-toCircle: Circumference and AreaCircumference is 2πr, area is πr². Here's how radius, diameter and π fit together, both formulas worked through, and how not to mix them up.How-toHow to Find the Area of a Triangle: Base × Height and Heron's FormulaTwo reliable ways to find a triangle's area: half base times height when you know the height, and Heron's formula when you only know the three sides.ExplainerThe Pythagorean Theorem ExplainedIn a right triangle, a² + b² = c². Here's what the formula means, a worked example, how to find any side, and where it's used in real life.How-toHow to Calculate VolumeVolume is the space inside a shape. Here's how to find it for boxes, cylinders and spheres, and why keeping your units consistent is the whole game.How-toHow to Calculate the Square Metres of a RoomFind a room's area by multiplying length by width. Here's the method for rectangular, L-shaped and round rooms, and why area drives your material orders.How-toHow Many Tiles Do You Need? (Floor and Wall)Estimate tiles from the area to cover and one tile's size, then add for cuts and waste. Here's the method, with an example and the 10% rule.