Hexagon Size Calculator
Choose which measurement you have, the side, across the flats, across the corners or the area, and enter it. The calculator works out all the others for a regular hexagon.
- Start from any size
- Flats and corners
- Area and perimeter
Use any unit. Results are in the same unit, with area in that unit squared.
A regular hexagon is six equal triangles. Each side equals the distance from the centre to a corner, so across the corners is exactly twice the side. Across the flats is the side times √3, about 1.732. Every other measurement follows from these.
Hexagon size chart
From the side length. Search for a size.
| Side | Across flats | Across corners | Perimeter | Area |
|---|---|---|---|---|
| 1 | 1.732 | 2 | 6 | 2.598 |
| 2 | 3.464 | 4 | 12 | 10.39 |
| 5 | 8.66 | 10 | 30 | 64.95 |
| 10 | 17.32 | 20 | 60 | 259.8 |
| 15 | 25.98 | 30 | 90 | 584.6 |
| 20 | 34.64 | 40 | 120 | 1039 |
| 30 | 51.96 | 60 | 180 | 2338 |
Across flats = side × 1.732. Across corners = side × 2. Area = side² × 2.598.
Side length and size
In centimetres. Slide the side length.
Area grows with the square of the side. Doubling the side gives four times the area.
How to work out a hexagon
From the side. Step through it.
Find the side
Or convert from what you have.
Hex keys and nuts are named by the width across flats, such as a 10 mm spanner or a 5 mm Allen key.
Flats, corners or side
Which size to quote. Compare them.
The narrower width, between parallel sides.
The widest width, point to point.
One edge of the hexagon.
Hexagon tiles are usually sold by the side or corner-to-corner size. Check the product sheet, as shops vary.
Making a hexagon
Cutting and building. Tick each item.
Tick each item as you go.
For a timber hexagon frame, cut each piece with 30° mitres on both ends. Six pieces at 60° joints close the shape.
What you get
Every hexagon size. Each tile explains one result.
Length of one edge.
Narrow width.
Wide width.
Inside the shape.
120° inside.
The inside angles of a regular hexagon are always 120°, and the outside angles 60°.
Frequently Asked Questions
No question matches that search.
How do I find the area of a hexagon?
Area = 3√3 ÷ 2 × side², about 2.598 × side².
What is across flats on a hexagon?
The width between two parallel sides. It is the side × 1.732.
What is across corners?
The width from one point to the opposite point, exactly twice the side.
How do I get the side from across flats?
Divide across flats by 1.732.
What angle do I cut for a hexagon?
30° mitres on each end of six equal pieces.
How many triangles are in a hexagon?
Six equal equilateral triangles.
What is the perimeter of a hexagon?
Six times the side length.
Any hexagon from one number
Enter the size you know and get every other measurement. Whether you are cutting timber, laying tiles or choosing a spanner, the numbers are ready.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.