Calculator Input
Plotly Graph
Example Data Table
| Known Value | Input | Perimeter | Area | Apothem |
|---|---|---|---|---|
| Side Length | 10 | 70.0000 | 363.3914 | 10.3821 |
| Perimeter | 84 | 84.0000 | 523.2836 | 12.4591 |
| Area | 500 | 82.1041 | 500.0000 | 12.1793 |
Formula Used
For a regular heptagon, the side count is fixed at 7.
Perimeter: P = 7s
Area: A = (P × a) / 2
Area from side: A = 7s² / [4 tan(π / 7)]
Apothem: a = s / [2 tan(π / 7)]
Circumradius: R = s / [2 sin(π / 7)]
Interior angle: ((7 - 2) × 180) / 7
Exterior angle: 360 / 7
Diagonals: 7(7 - 3) / 2 = 14
Short diagonal: d₁ = 2R sin(2π / 7)
Long diagonal: d₂ = 2R sin(3π / 7)
How to Use This Calculator
- Select the known heptagon measurement from the dropdown.
- Enter the numeric value for that measurement.
- Add a unit label like cm, m, or inches.
- Choose the decimal precision you prefer.
- Click the calculate button to generate all values.
- Review the result panel above the form.
- Use CSV or PDF export for saved records.
- Check the graph to compare geometric measures visually.
Frequently Asked Questions
1. What is a 7 sided polygon?
A 7 sided polygon is called a heptagon. When all sides and angles are equal, it becomes a regular heptagon.
2. Does this calculator handle irregular heptagons?
No. This calculator is built for regular heptagons only. Irregular shapes need separate side lengths, angles, or coordinate geometry.
3. What value should I enter first?
Enter whichever regular heptagon measurement you already know. Good choices include side length, perimeter, area, apothem, or circumradius.
4. Why are there two diagonal values?
A regular heptagon has two distinct diagonal lengths. One connects vertices two steps apart. The other connects vertices three steps apart.
5. What is the interior angle of a regular heptagon?
Each interior angle equals 900 divided by 7 degrees. That is about 128.5714 degrees.
6. How is the area calculated?
The area uses either side length or perimeter and apothem. The common formula is area equals perimeter times apothem divided by two.
7. Can I use any unit?
Yes. You can enter any unit label. The calculator keeps measurements consistent as long as your input stays in one unit system.
8. What do CSV and PDF exports include?
They include the calculated heptagon values shown in the results section. This makes recordkeeping and sharing much easier.