A regular octagon has eight equal sides and equal angles. The standard area formula uses only side length, making it quick to calculate from one measurement.
⚠This calculator assumes a regular octagon. Side length must be positive.
How Octagon Area Works
The regular octagon can be decomposed into central triangles or viewed as a square with corners cut off. Both approaches lead to the same formula.
Eight Sides
A regular octagon has eight equal sides.
Perimeter
Perimeter equals 8s.
Apothem
The center-to-side distance is also shown.
Regular Only
Irregular octagons need different methods.
💡 Example: For s=5, A=2(1+√2)(25)=120.711 and perimeter=40.
Applications of Octagon Area
SignsTile LayoutsArchitectureDesign Grids
Frequently Asked Questions
What is an octagon area calculator?▼
It calculates the area of a regular octagon from side length.
What is the regular octagon area formula?▼
The formula is A = 2(1+√2)s², where s is the side length.
How do I use this calculator?▼
Enter the side length and click Calculate to get area, perimeter, and apothem.
Does this work for irregular octagons?▼
No. It assumes a regular octagon with eight equal sides and equal angles.
Where is octagon area used?▼
It is used for signs, tiles, architecture, design grids, and geometry problems.
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