⭕Circle Calculator
Find a circle's diameter, circumference and area.
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About this calculator
Free Circle Calculator — find the diameter, circumference and area of a circle from its radius.
How to use
Enter your Radius above — the result updates instantly as you type or drag the sliders. It's free and needs no sign-up.
Frequently Asked Questions
What does the Circle Calculator do? ▼
Find a circle's diameter, circumference and area.
How does the Circle Calculator work out the answer? ▼
The Circle Calculator applies the standard mathematical formula for this problem to the values you enter and returns the exact result instantly.
How do I use the Circle Calculator? ▼
Enter your values using the input fields or sliders. The result updates instantly — no submit button needed. All calculations run in your browser.
Can I use the Circle Calculator for homework or study? ▼
Absolutely. The Circle Calculator is a great way to check your work and understand the steps. Try solving the problem yourself first, then compare with the calculator.
Is the Circle Calculator free? ▼
Yes — completely free. No sign-up, no download, and no account required. Works in any browser.