Quick Answer: To use a battle map in Roll20, create a new game, open the campaign, upload your map image to the Asset Library, drag it onto the Map layer of your scene, and use the Grid Configuration tool to align Roll20's grid to the map. Always use the gridless version of your map. Set the grid scale by matching the pixel width of one grid square to Roll20's unit settings. For Black Lantern Forge maps at 4096 x 4096 pixels on a 30x30 grid, each square is 136 pixels wide.
Roll20 is the most widely used virtual tabletop for Dungeons and Dragons, and for good reason. It runs entirely in a browser, requires no software installation, and your players can join a session from anywhere with a link. But the first time you try to get a battle map looking right inside a Roll20 campaign, especially getting the grid to align correctly, it takes more fiddling than it should.
Here is the full process, from uploading your first map file to running a clean, grid-aligned session your players can actually play on.
What You Need Before You Start
Before opening Roll20, have two things ready.
First, the gridless version of your battle map as a PNG file. Roll20 draws its own grid over the map image. If you import a gridded map, you will end up with two overlapping grids that do not align, which makes the map unplayable. Always use the gridless file in Roll20 and let the platform handle the grid.
Second, the pixel dimensions and grid square count of your map. For Black Lantern Forge maps, both values are consistent across every file: 4096 x 4096 pixels on a 30x30 grid. Having these numbers ready before you open Roll20 makes the grid configuration step fast and accurate.
Step 1: Create Your Campaign and Open the Map
Log into Roll20 and create a new game from your dashboard. Once the game is created, click Launch Game to open the campaign editor.
Inside the campaign, you will see a blank canvas. This is your first map page. Roll20 calls these pages rather than scenes. Each page holds one map, and you can create as many pages as your campaign needs, one for each encounter or location.
Click the gear icon next to the page name at the top of the screen to open the page settings. This is where you will configure the grid and dimensions before uploading your map.
Step 2: Configure Page Settings
In the page settings, set the page dimensions to match your map image. Roll20 measures pages in units, where one unit equals one grid square by default. For a 30x30 map, set the page width and height to 30 units each.
Set the scale to 5 feet per unit, which is the standard DnD movement scale where one grid square equals 5 feet of in-game space.
Leave the grid turned on. Roll20 will draw this grid over your map image once you upload it. Do not turn the grid off here.
Step 3: Upload Your Map to the Asset Library
In the right-hand sidebar, click the Image icon to open the Art Library. At the top of the panel, click Upload and select your gridless PNG file.
Roll20 supports PNG, JPEG, and WebP files. PNG is the best choice for battle maps because it preserves full image quality. Files from the Dark Encounter Battle Maps Pack and the Shadows Beneath the Tavern Map Pack are delivered as PNGs and can be uploaded directly without any conversion or resizing.
Once uploaded, the file appears in your Art Library and is available to use across any campaign in your account.
Step 4: Place the Map on the Map Layer
This step is where most new Roll20 users make a mistake. Roll20 has multiple layers: the Map layer, the Objects layer, the GM Info layer, and the Token layer. Your battle map image needs to go on the Map layer specifically.
In the toolbar on the left side of the screen, click the layers icon and make sure the Map layer is selected before you drag your image onto the canvas.
Drag your uploaded map from the Art Library onto the canvas. A resize dialog will appear. Set the dimensions to match your page size. For a 30x30 page, size the image so it fills the full canvas edge to edge. Use the lock aspect ratio option to keep proportions correct while resizing.
If the image does not fill the canvas exactly, click and drag the corners to extend it to the edges. Precise alignment here is important because any gap between the image edge and the page edge will show blank canvas during play.
Step 5: Align the Grid
With your map placed on the Map layer, Roll20's default grid will appear over it. In most cases it will not align perfectly with the map's artwork on the first attempt. The Grid Configuration tool fixes this.
Click the gear icon on the page tab and scroll down to the Grid section. You will see options for grid color, line width, and grid alignment.
For Black Lantern Forge maps, the grid should align automatically if the page dimensions and image size are set correctly, because the maps are built to a consistent 30x30 grid with the artwork starting at the top-left corner of the image. If the grid is slightly off, use the X Offset and Y Offset fields to nudge it into position. Small adjustments of one to three pixels in either direction will correct minor misalignment.
Set the grid color to something that reads clearly over the map artwork without obscuring it. A light grey or white at reduced opacity works well for most environments. For darker maps like the Smuggler's Undercrypt or the Ritual Chamber of Embers, a slightly brighter grid line helps players count squares without squinting.
Step 6: Set Up Dynamic Lighting
Dynamic lighting in Roll20 is available on Pro accounts and significantly improves the player experience by hiding unexplored areas and blocking sight behind walls.
To enable it, open the page settings and turn on Dynamic Lighting. Then use the Dynamic Lighting layer to draw walls along every room boundary, doorway, and corridor in your map.
This takes preparation time but pays off immediately during play. When a player token moves through a door, the room beyond reveals itself in real time. Areas behind walls stay dark. The map becomes a discovery experience rather than a static image.
For maps with multiple connected rooms, like the Gilded Mug Tavern layouts from the Shadows Beneath the Tavern Map Pack, dynamic lighting transforms the map from a flat tactical surface into an environment players genuinely explore. Drawing walls for a 10-room map takes around 15 to 20 minutes of prep, and that work carries across every session the map is used.
If you are on a free Roll20 account, the fog of war tool provides a simpler version of the same effect. You can manually reveal sections of the map as players explore by drawing revealed areas with the fog brush.
Step 7: Add Tokens and Test Before the Session
Before your players join, add your player character tokens and at least one NPC or monster token to the scene. Move the tokens around the map to confirm the grid snaps correctly and that one grid square corresponds to one movement unit.
Check that the map fills the canvas edge to edge with no blank borders visible. Check that the grid aligns with the map's artwork. If you have dynamic lighting enabled, move a token through several rooms to verify that sight lines and wall placements are working as expected.
Two minutes of testing before the session saves ten minutes of troubleshooting in front of your players.
Common Roll20 Issues and Fixes
Grid does not align with the map artwork.
The most common cause is a mismatch between the page dimensions and the image size. Confirm the page is set to 30x30 units and the image is sized to fill the canvas exactly. Use the X Offset and Y Offset fields in page settings to fine-tune alignment.
Map image looks blurry or soft.
Roll20 compresses images automatically for free accounts. Upgrading to a Plus or Pro account removes compression limits. Alternatively, convert the PNG to WebP before uploading, as WebP often compresses better at equivalent quality than PNG in Roll20's pipeline.
Two grids are visible on the map.
This means a gridded map image was imported instead of the gridless version. Replace the image on the Map layer with the gridless version of the same map.
Map image has white borders or does not fill the page.
The image was not sized to fill the full canvas during placement. Click the image to select it, hold Alt, and drag the corners to extend it to the page edges.
Dynamic lighting is not working.
Dynamic lighting requires a Pro account on Roll20. If you are on a free or Plus account, use the fog of war tool instead for manual reveal control.
Running the Session
Once your page is configured and tested, share the campaign link with your players. They join through a browser with no installation required. When they enter the campaign they will see the map, their tokens, and the grid.
As the DM, you control what players see. You can switch pages mid-session to change locations, reveal fog of war areas as players explore, and move tokens on any layer without players seeing your GM info.
Roll20's simplicity is its biggest advantage. Players who have never used a VTT can sit down in a session and understand what they are looking at within minutes. The learning curve sits almost entirely on the DM side during setup, and most of that setup becomes routine after two or three sessions.
The Dark Encounter Battle Maps Pack gives you 10 environments including outdoor ambushes, forest trails, dungeon caverns, and corrupted ruins, all at 4096 x 4096 pixels and ready to import into Roll20 using the steps above. The Shadows Beneath the Tavern Map Pack covers two full tavern interiors, connected underground tunnels, a ritual chamber, and a market district across 10 maps at the same resolution and grid standard.
Both packs are $14.99 with instant download and lifetime access.
Frequently Asked Questions
What image size should I use for Roll20 battle maps?
Battle maps for Roll20 should be at least 4096 x 4096 pixels for a 30x30 grid. This resolution ensures the map displays sharply at full size without blurring when players zoom in. Black Lantern Forge builds all maps at 4096 x 4096 pixels specifically to meet this standard across Roll20, Foundry VTT, and Owlbear Rodeo.
Should I use gridded or gridless maps in Roll20?
Always use the gridless version in Roll20. Roll20 renders its own grid over the map image. Importing a gridded map creates two overlapping grids that do not align, making the map difficult to use during play. Import the gridless file and configure the grid scale in the page settings.
How do I align the grid in Roll20?
Open the page settings and scroll to the Grid section. Set the page dimensions to match your map's grid count (30x30 for Black Lantern Forge maps). If the grid is slightly off, use the X Offset and Y Offset fields to nudge it into alignment. For well-built maps with artwork starting at the image corner, offsets of zero should work without adjustment.
Does Roll20 support fog of war?
Yes. Roll20 offers two fog of war options. The standard fog of war tool is available on all account tiers and allows manual reveal control. Dynamic lighting, which automatically reveals areas based on token sight lines and wall placements, requires a Pro account.
Can I use Roll20 for free with paid battle maps?
Yes. Roll20's free tier supports image uploads and manual fog of war. You can run full sessions with high-quality battle maps on a free account. Dynamic lighting and some automation features require a paid Roll20 subscription, but the core map display and grid functionality is available at no cost.
What layer should battle maps go on in Roll20?
Battle maps should always be placed on the Map layer in Roll20. Placing a map image on the Objects or Token layer will cause it to interfere with tokens and other game elements. Select the Map layer in the toolbar before dragging your image onto the canvas.
