To roll dice in Foundry VTT, type a formula such as /r 1d20+5 in the chat box or click the dice tray icon in the right-hand sidebar — Foundry parses the notation, generates the result with JavaScript's built-in random source, and posts each individual die plus the total into the chat log for everyone at the table to see. The platform ships with a complete dice engine that understands standard polyhedral notation, modifiers, and grouping operators, so most roll expressions work without any extra modules installed. Players and the Game Master alike share the same command set, and every roll is archived in the chat history for review later. Whether running a one-shot at the table or managing a long-running campaign, the built-in roller covers attacks, saves, damage, and advantage/disadvantage rolls out of the box. This guide walks through how to use Foundry's native dice system, when a browser-based alternative becomes useful, and the formulas you will reach for most often during play. We will also look at the math behind common dice pools so you can set expectations at the table before a critical roll.
Rolling Dice in Foundry VTT (Native Methods)
Foundry VTT includes a dice engine that activates the moment you type into the chat bar at the bottom of the screen. Every participant at the virtual table — players and Game Master alike — can use the same set of commands, and rolls are logged in the chat history for review later. There are two primary ways to roll: typing a slash command in chat, or using the dice tray icon in the right sidebar. Both produce identical results; the difference is workflow.
Chat commands for dice
The simplest way to roll is by typing a slash command followed by standard dice notation:
- /r 1d20 — rolls one twenty-sided die and posts the result publicly in chat.
- /r 1d20+5 — rolls a d20 and adds a modifier of 5, used for attack rolls and ability checks with an ability score bonus.
- /r 4d6kh3 — rolls four six-sided dice and keeps the highest three, the classic method for generating an ability score during character creation.
- /r 2d6+3 — rolls two six-sided dice for damage with a modifier, common for longsword attacks at mid levels.
Foundry accepts the full dice notation grammar, including kh (keep highest), kl (keep lowest), dh (drop highest), dl (drop lowest), r (re-roll once), ! (exploding dice), and cs/cf (critical success/critical failure thresholds). The chat message shows every individual die face alongside the total, so players can verify the math at a glance. If the GM has configured blind rolls, the result is hidden from other players until the GM reveals it.
Using the dice tray icon
For players who prefer not to type formulas, Foundry displays a dice tray icon in the right sidebar. Clicking it opens a tray where you can drag virtual dice into a rolling area, then click again to roll. This is the fastest option for quick attacks when the modifier is already known. Right-click the icon for advanced options, including blind rolls (results hidden from other players until the GM reveals them) and self rolls (visible only to you). Holding Shift while clicking the dice tray icon opens the configuration menu, where you toggle between 2D and 3D rendering and adjust other roll behaviors. If you want tumbling 3D dice, install a community module such as Dice So Nice, which replaces the default 2D tray with a physics-driven 3D roller.
Configuring rolls and visibility
The Game Master can configure Foundry so that players see all rolls, see only their own, or hide every result until the GM chooses to reveal it — useful for high-trust groups and for paranoid ones. You can also bind dice formulas to character sheet attributes so an attack roll button on the character sheet automatically rolls with the correct modifier. Many official game systems, including the D&D; 5e and Pathfinder 2e systems, ship with these integrations ready to use.
How to Roll Dice with the Browser-Based Dice Roller
When you want to roll dice outside of a Foundry session — for prep work, quick rules questions, character creation away from the table, or a session where the host's server is down — a browser-based Dice Roller handles the same notation without needing a VTT connection. If you prefer a walkthrough focused on the browser tool itself, the guide to rolling dice online from d4 to d20 covers it in depth. Follow these steps to produce a roll in your browser:
- Pick a dice type — d4, d6, d8, d10, d12, d20 — or tap Custom and type any number of sides from 2 up to 1000 for an exotic die such as a d100 or d3.
- Set how many dice to roll using the − and + stepper, then press the Roll button.
- Read each individual result, the running total, your recent roll history, and session statistics displayed below the controls.
Every roll uses crypto.getRandomValues(), the browser's cryptographically secure pseudo-random number generator, so each face is equally likely and the distribution is statistically uniform. The tool supports up to 12 dice of the same type in a single batch and keeps a short running history plus session statistics so you can watch averages settle toward the expected value over time. Because everything runs client-side, it works offline once the page has loaded and never sends your rolls to any server.
When to Use Foundry vs a Browser Dice Roller
Foundry VTT is the right tool when the whole group is online and connected to the game server — the roll feeds straight into the chat log and the GM's tracking tools, including hit point adjustments, condition tracking, and combat turn order. A browser-based roller becomes useful in several situations:
- Prep and character building. Roll ability scores, hit points, and starting gold without spinning up a session, keeping results private until you are ready to share.
- Server outages. If the host loses internet or the server crashes mid-session, a browser roller keeps the game moving while you troubleshoot.
- Rules clarification. When a question about probability comes up — "how often does a d20 land on a natural 20?" — a quick batch of test rolls gives a real answer.
- Quick decisions. Settle "who goes first?" or "does the merchant have what we need?" with an instant roll, no VTT required.
The browser tool also doubles as a teaching aid because the running history and average-total statistics make probability distributions visible as you roll.
Common Dice Formulas for Tabletop RPGs
Most rolls you make in a tabletop RPG fall into a handful of recurring patterns. The table below lists the formulas, the dice involved, and the most common use case for each. Foundry accepts these formulas directly in chat.
| Formula | Dice | Common Use |
|---|---|---|
| 1d20+mod | d20 | Attack rolls, saving throws, ability checks |
| 2d20kh1+mod | 2d20 keep highest | Rolling with advantage (D&D; 5e) |
| 2d20kl1+mod | 2d20 keep lowest | Rolling with disadvantage (D&D; 5e) |
| 4d6kh3 | 4d6 keep highest 3 | Generating a single ability score |
| 2d6+mod | 2d6 | Longsword damage and similar two-handed weapons |
| 1d8+mod | d8 | Rapier, longsword one-handed, shortbow |
| 1d12+mod | d12 | Greataxe and other heavy two-handed weapons |
| 1d100 | d100 | Percentile rolls, wild surge tables, loot tiers |
The kh, kl, and mod parts are part of standard dice notation, so a character sheet's notation should work without conversion. If you ever type a formula that does not parse, Foundry highlights it in red and offers a hint at the bottom of the chat box.
Understanding Dice Probability and Why It Matters
Once you start rolling more than one die at a time, the math shifts from uniform to bell-shaped. A single d20 lands on every face 5% of the time — completely flat. But the sum of two or more dice forms a curve where middle values come up more often than extremes.
Take 2d6, the most familiar dice pool. There is only one way to roll a 2 (1+1) and only one way to roll a 12 (6+6), so those totals are rare. There are six ways to roll a 7 — (1,6), (2,5), (3,4), (4,3), (5,2), (6,1) — so 7 sits at the peak of the curve and is by far the most common total. This is why craps players bet on 7, why Monopoly's jail-break rule uses the same dice, and why teachers use dice to introduce the central limit theorem.
The browser Dice Roller exposes this directly: roll 2d6 a few dozen times and the running average settles close to 7, while the running totals and session statistics reveal a triangular distribution. Watching the distribution form in real time is a useful teaching tool and a quick way for new players to internalize why a greatsword is mechanically safer than a greataxe — the 2d6 damage die concentrates results near the expected 7 while the 1d12 spreads them evenly from 1 to 12.
For Game Masters, recognizing the shape of the curve also informs encounter design. If you want a fight where crits feel common, reach for dice pools that include exploding or maximum-roll mechanics. If you want steady, predictable damage, prefer dice that sum into a tight bell curve. Either way, knowing what the dice are doing underneath the numbers helps you build challenges that match the tone of your session.