Regular Hexagon Calculator
Enter one known dimension to calculate all major hexagon measurements instantly.
What this hex size calculator does
This tool solves the geometry of a regular hexagon from a single known value. A regular hexagon has six equal sides and six equal angles, which means every key measurement can be derived from one input.
If you know side length, distance across flats, distance across corners, apothem, perimeter, or area, the calculator returns all of the others in one step.
Hexagon terms explained
1) Side length (s)
The length of one outside edge of the hexagon.
2) Across flats (flat-to-flat)
The distance between two opposite parallel sides. This is common in machining and wrench sizing contexts.
3) Across corners (point-to-point)
The distance from one vertex directly across to the opposite vertex. This is the largest diameter of the hexagon.
4) Apothem
The distance from the center of the hexagon to the middle of any side.
5) Perimeter
The total outer boundary length: six times the side length.
6) Area
The space enclosed by the hexagon.
Core formulas used
For a regular hexagon with side length s:
- Across corners = 2s
- Across flats = s√3
- Apothem = (s√3)/2
- Perimeter = 6s
- Area = (3√3/2)s²
These relationships are exact and come from splitting the hexagon into six equilateral triangles.
How to use the calculator
- Select the measurement type you already know.
- Enter the numeric value.
- Optionally provide a unit label (like mm, in, or cm).
- Click Calculate to see all converted results.
Practical applications
A hex size calculator is useful in many real-world tasks:
- Mechanical design: converting between hex stock dimensions and area for material estimates.
- CNC and fabrication: validating dimensions before cutting.
- 3D printing: sizing hex recesses and nut traps.
- Architecture and graphics: generating hex grids and layout geometry.
- Education: checking geometry homework and formula understanding.
Example
If your hex side length is 10 mm, then:
- Across corners = 20 mm
- Across flats ≈ 17.3205 mm
- Perimeter = 60 mm
- Area ≈ 259.8076 mm²
FAQ
Does this work for irregular hexagons?
No. This calculator assumes all sides and angles are equal (regular hexagon).
Which dimension is best to start with?
Use whichever value you can measure most reliably. In production settings, across flats and side length are often the easiest to verify.
Can I use any unit?
Yes. The calculator is unit-agnostic. Just enter your value and label (mm, in, ft, etc.), and outputs remain in that same unit (area uses squared units).