Hex Map Generator

Hex Map Generator

Builds a wilderness hex map by simulating the terrain tables from Appendix B of the 1st edition Dungeon Masters Guide (p.173).

Open the generator

How it generates

It starts from a single tile in the middle of the board and works outwards. Each new tile is rolled from the terrain of a tile next to it, using a d20 against that terrain's column. Forest tends to beget forest, mountains give way to hills, and so on, which is what makes the result read as a landscape rather than noise.

Water and Valley are ignored when rolling the next tile, exactly as the original tables specify, so a pond does not reset the terrain around it.

The generator renames three of the original terrains: Scrub is Brush, Pond is Water, and Depression is Valley.

Controls

Tile labels switches what is drawn on each tile:

• Description writes the terrain name.
• Image draws a symbol for the terrain instead. Useful at the smaller sizes where names get cramped.

Map size sets how many tiles fit. The names describe the map, so a larger map means smaller hexes:

Size	Hex radius	Roughly
Small	100	a couple of dozen tiles
Medium	60	around 50 tiles
Large	30	a few hundred tiles
Extra Large	19	around 900 tiles at desktop width

The exact count depends on your window, since the grid fills whatever space the canvas has.

Generate rolls a fresh map at the current size. Save downloads the map as a PNG, with the date and time in the filename. The ? button opens the terrain key, which also explains the source tables.

Notes

• The size is carried in the URL (?s=m), so a particular size can be bookmarked or shared.
• Generating measures the canvas first, so resizing the window or collapsing the sidebar and pressing Generate refits the map.
• Whole tiles only: the grid is centred with a margin, so nothing is clipped at the edges.