What formulas are used?

Diameter d = 2r · circumference C = 2πr · area A = πr² · arc length L = θ·r (θ in radians) · sector area S = ½·θ·r². The 90° slice uses θ = π/2.

Can I enter diameter instead of radius?

Radius is the input here. To use diameter, divide it by 2 first (or use a calculator) and enter the radius.

Same as the input — if you enter radius in cm, area comes out in cm² and circumference in cm.

It's the most common sector in practice (quadrant). The formula shown generalizes to any angle θ in radians.

Yes — entirely in your browser.

Area, circumference, diameter — and 90° arc & sector — from radius.

100% private — no uploads Free & unlimited Read tutorial

Watch a quick simulation of this tool in action — no file needed.

Follow these steps — everything happens instantly in your browser.

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Step 1. Enter the radius (any positive number).
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Step 2. See diameter, circumference, area, 90° arc and 90° sector update instantly.

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