Most battlemaps that disappoint at the table are not badly drawn. They are the wrong size, locked to the wrong grid, or supplied in one variant when the scene needed three. Four things decide whether a map earns its place in your library.
Resolution, measured per square
Pixel dimensions on their own tell you nothing. What matters is pixels per square, because that is what determines whether the map holds up when a token stands on it. Roll20 works at 70 pixels per square, Foundry VTT defaults to 100, and print at 300 DPI needs 300 for a one-inch square. A 30 by 20 square dungeon is 2100 by 1400 for Roll20 and 9000 by 6000 for print. Below about 50 pixels per square, detail turns to mush on a screen and is unprintable.
Gridless beats gridded
A gridless map works on every system at every scale, and a grid takes seconds to add with the grid overlay tool. A map with the grid painted into the artwork is locked to whatever scale the artist chose, and removing it means editing the image. If you are choosing between two otherwise equal maps, take the gridless one and keep it as your master copy.
Variants matter more than locations
The thing that runs out in a long campaign is not places, it is versions of places. The party will revisit the same tavern in daylight, at night, on fire, and after the fight. A map supplied with lighting and season variants does four jobs; the same map supplied once does one. This is the single most underrated thing to look for in a pack, and it is why map bundles are better value than individual maps even when the per-map price looks worse.
File format, briefly
JPG for large outdoor and dungeon maps where file size matters and there is no transparency. PNG where the map has transparent regions or hard linework. WebP is smaller than both at equal quality and every current virtual tabletop and browser supports it, so prefer it where the platform allows.
The same map file serves both, but the preparation differs and the mistakes are different.
On a virtual tabletop, set the scene's grid to match the map rather than scaling the map to match the grid. Resampling a map to fit a grid setting is what produces the soft, slightly-wrong look that makes a good map feel cheap. Our guides to importing battlemaps into Foundry and how the two platforms differ cover the per-platform steps.
In print, grid first and split second, so the grid runs continuously across the sheets. The map splitter tiles a large map to A4 or Letter. Aim for 200 DPI unless you are going to a print shop, because most home printers cannot resolve more than that and the larger file buys you nothing.
On a TV or tablet laid flat, the grid has to match physical miniatures rather than pixels, so measure a real inch on the screen and set the square size to that. The tabletop display tool pushes a map and fog to a second screen, and running maps on a TV or projector covers the setup.
For choosing what to buy in the first place, building a battlemap library covers the bundle-versus-subscription decision, and how big a battlemap should be goes deeper on sizing encounters.
FAQ
What resolution should a D&D battlemap be?
Work back from the square. Roll20 expects 70 pixels per square, Foundry VTT defaults to 100, and print at 300 DPI needs 300 pixels for a one-inch square. A 30 by 20 square dungeon is therefore 2100 by 1400 for Roll20 and 9000 by 6000 for print. Anything below 50 pixels per square looks soft on a screen and unusable on paper.
Are gridless or gridded battlemaps better?
Gridless, in almost every case. A gridless map works on any system and at any scale, and you can add a grid in seconds with a grid overlay tool. A map with a grid baked in is locked to whatever scale the artist chose, and you cannot remove it without editing the artwork.
What file format should battlemaps be in?
JPG for large outdoor and dungeon maps, where the file size saving matters and there is no transparency. PNG where the map has transparent areas or hard-edged linework. WebP is smaller than both at the same quality and is supported by every current virtual tabletop and browser, so it is worth using where the platform accepts it.
Can I use these battlemaps in Roll20 and Foundry VTT?
Yes. They are standard image files, so any virtual tabletop that accepts an image upload will take them, including Roll20, Foundry VTT, Fantasy Grounds, Owlbear Rodeo and Alchemy. Set the scene grid size to match the map rather than resizing the map to match the grid.
How do I print a battlemap larger than one sheet of paper?
Add the grid first, then split the map into page-sized tiles so the grid stays continuous across the join. Doing it the other way round means aligning the grid separately on every sheet. The map splitter tool handles the tiling for A4 and Letter.
How many battlemaps does a campaign actually need?
Fewer distinct maps than most DMs expect, and more variants of each. A tavern, a dungeon corridor set, a forest track, a town street and a cave system will cover the majority of encounters in a typical campaign. What runs out first is not locations but lighting and season variants of the locations you already use.