Decagon Calculator
Calculate the area and perimeter of a regular decagon (10-sided polygon) from its side length.
- Perimeter
- 50
Formula: A = (5/2) × a² × √(5 + 2√5)
About Decagon Calculator
Decagon Calculator is a free online calculator that gives you an instant, accurate result as you type. Calculate the area and perimeter of a regular decagon (10-sided polygon) from its side length.
The calculation uses the standard formula A = (5/2) × a² × √(5 + 2√5) and updates live with every change to the inputs. Everything runs client-side in your browser — fast, private, and free to use as often as you like.
Each interior angle of a regular decagon is 144 degrees, and its area is roughly 7.69 times the square of its side.
Frequently Asked Questions
Is Decagon Calculator free to use?
Yes. Decagon Calculator is completely free, with no sign-up, no downloads, and no usage limits. You can use it as many times as you like on any device with a web browser.
How accurate is this calculator?
The calculator applies the standard formula (A = (5/2) × a² × √(5 + 2√5)) with full floating-point precision and rounds only the displayed result. For most practical purposes the results are exact.
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