Roll virtual dice for board games, RPGs and probability experiments. Supports d4, d6, d8, d10, d12, d20 and d100, with custom counts and modifiers (e.g. 3d6 + 2). Uses cryptographically secure random numbers.
Added to the sum (e.g. +2 for skill bonus)
Online dice rollers are useful for far more than just gaming. Tabletop role-playing games like Dungeons & Dragons (D&D), board games that have lost their physical dice (Monopoly, Ludo, Snakes & Ladders), classroom probability lessons, group decision-making, and statistics demonstrations all benefit from a reliable digital roller. This tool supports all standard die types - d4 (4-sided pyramid), d6 (cube, the standard die), d8, d10 (used for percentage when paired), d12, d20 (the iconic RPG die), and d100 (percentile die) - plus arbitrary counts and modifiers in the standard 'XdY+Z' notation gamers will recognise instantly.
What makes this roller fair is the use of cryptographically-secure randomness via window.crypto.getRandomValues(). This is the same level of randomness used for security keys, not the predictable pseudo-random Math.random() that most quick implementations use. For RPG gameplay where tense moments depend on a single d20 result, this means rolls are genuinely unpredictable and uniform - no subtle bias toward certain numbers, no patterns to exploit. Each die is also rolled independently, so 3d6 means three truly separate rolls summed, exactly like physical dice.
Pick the die type (or a custom set).
Enter number of dice and modifier.
Click Roll. See individual results, sum and total.
Each roll uses crypto.getRandomValues() - cryptographically secure random integers. Each die is independent and uniformly distributed across its faces.
Total = Σ rolls + modifier
Standard dice notation: 'XdY+Z' means roll X dice with Y sides each and add modifier Z. Examples: 1d20+5 (one twenty-sided die plus 5, common D&D attack roll), 3d6 (three six-sided dice, classic D&D ability score, range 3-18 with mean 10.5), 4d6 drop lowest (four six-sided dice, keep top three - slightly higher mean, common alternate D&D method). The roller supports the standard expressions and shows individual die results so you can verify the sum.
Each die uses crypto.getRandomValues() to fetch random bytes from the OS entropy pool, then maps them to the die range using rejection sampling to avoid modulo bias. This guarantees each face has exactly equal probability - 1/6 for a d6, 1/20 for a d20, 1/100 for a d100. Multiple dice are rolled in sequence, each independent, so the joint distribution matches physical dice exactly.
Probability distributions matter for gameplay design: 1d20 is uniform (5% chance per number), feels swingy. 3d6 is bell-curved (sum range 3-18, mean 10.5, most rolls cluster around 10-11) - feels more 'reliable' but rare extremes. Knowing these distributions helps players estimate odds: rolling 15+ on a d20 is 30% chance; rolling 15+ on 3d6 is only ~9%. Both useful for different game design intents.
Roll: 14. Total: 14 + 5 = 19. If target's armor class is 17, the attack hits. This is the most common dice operation in D&D 5e - the d20 + modifier vs target number system underlies attacks, skill checks and saving throws.
Rolls: 4, 6, 5, 2. Drop lowest (2). Sum: 4 + 6 + 5 = 15. Generates ability scores in the 3-18 range with mean ~12.24, slightly higher than straight 3d6 (mean 10.5). Standard for D&D character creation.
Rolls: 3, 4. Sum: 7. The most common sum (16.67% probability) - explains why '7' positions on Catan boards see the most action.
Yes - crypto.getRandomValues uses the OS's secure RNG. Each roll is unpredictable and uniform.
D&D and most tabletop RPGs use a d20 for skill checks, attacks and saving throws. Roll high to succeed.
Three six-sided dice rolled together; sum is the result. Range 3-18, mean 10.5. D&D ability scores are traditionally 3d6.
Faster than physical dice, you can roll dozens at once, results are tamper-evident (no fudging). Useful for online play and probability demos.
Date math, password generation, QR codes, IP subnets, base64 encoding, dew point, dice rolls, age calculations - none of these are 'big' problems individually, but they are the small frictions that interrupt your day. This tool runs entirely in your browser, has no popup, no chat widget and no tracking inside the calculation, so you can finish the task and move on.
Many tools in the Daily Utilities category complement each other - date difference + day counter + day-of-the-week, or password generator + QR code + base64 encoder. The related-tool grid links them together so you can move between adjacent problems in a click.
The Dice Roller is part of the Daily Utilities suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.
