I needed to figure out how many square miles are in a hexagon. Turns out, nobody wants to give a straight answer when all you know about the hexagon is the distance face-to-face, which is what we all use in the hex and chit world.

After relearning some geometry, this is the simplest possible approximation I can give you: a = (w / 1.732) * (1.5w)

That is, the area is the width “face to face” divided by 1.732, then multiply that by 1.5 times the width.

Example: A Greyhawk 30-mile hex has width 30. It’s area is about 779 square miles.

a = (30 / 1.7320) * (1.5 * 30)

a = (17.3210) * (45)

a = 779.4457

Which means if your stronghold-building wilderness-clearing 9th level Fighter wants a Greyhawk hex all to himself, he’s clearing almost 800 square miles of monsters. Get to it, Gutboy Barrelhouse!

This is the kind of formula I’d put on the second DM screen that you pull out only *in extremis. *Like how composition books have commonly-used formulae on the inside covers.

Watch this become by far the most useful thing I have ever done

EDIT: As was pointed out, my formula is off even as an estimate. I checked it against Red Orc’s linked calculator and I was extremely close to being off by doubling the area, so I changed the formula. Regarding Black Vulmea’s formula in the linked Promise City blog post, I guess you have the textbook formula but it looks like the above approximates to yours – close enough for horseshoes anyway. Thank you all for revealing my mathematical decrepitude!

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This entry was posted on March 13, 2018 at 11:57 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed.
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March 14, 2018 at 7:33 am |

Or you could’ve just checked my blog.

March 17, 2018 at 3:17 pm |

Your formula is off. You are getting an area much larger than the actual area. Draw a hex on some grid paper and count the squares.

March 20, 2018 at 4:57 pm |

I have a page bookmarked for working out the area of a hexagon because it’s only gamers that measure the size of a hexagon centre-to-centre through a perpendicular edge.

https://www.calculatorsoup.com/calculators/geometry-plane/polygon.php

Pretty sure you want to know A from twice the ‘inradius r’. For a 30 mile face-to-face distance (ie, r=15), that gives an area of 779.4 square miles.

March 25, 2018 at 12:25 pm |

Good catch, everyone. Thanks!