Free virtual dice roller and dice simulator for tabletop RPGs and board games: type any dice notation (3d6, 2d20kh1, 4d6dl1, d100) and roll instantly with cryptographically secure randomness. Below the roller you get something no other web roller offers in one place: exact probability distributions (computed by real combinatorics, not simulation), distribution charts, and a chi-square fairness test for your physical dice. No ads, no signup, no roll limits — 100% client-side, your rolls never leave your browser.
Press Roll — or pick a preset above.
2d20kh1+5 or click a preset.Rolls use crypto.getRandomValues() with rejection sampling — every face has exactly equal probability, with no modulo bias.
This roller understands full tabletop dice notation — the same language used by D&D players, AnyDice users and RPG forums:
| Notation | Meaning | Example use |
|---|---|---|
NdM | Roll N dice with M sides, sum them | 3d6 damage, 2d8 healing |
d20, d12… | Single die (N defaults to 1) | Attack rolls, saving throws |
d% / d100 | Percentile dice | Call of Cthulhu skill checks |
khK / klK | Keep highest / lowest K dice | 2d20kh1 = advantage |
dlD / dhD | Drop lowest / highest D dice | 4d6dl1 = D&D ability scores |
! | Exploding dice (max face rolls again) | 2d6! Savage Worlds style |
r | Reroll 1s once | 3d6r Great Weapon Fighting style |
+ / - | Modifiers and mixed pools | 1d20+5, 1d8+2d6-1 — roll multiple dice with modifiers |
Most online dice odds calculators use Monte Carlo simulation — they roll millions of virtual dice and the answer wobbles. This tool computes exact probabilities with pure combinatorics:
3d6, 8d6+2) — dynamic-programming convolution over every possible outcome.4d6dl1, 2d20kh1) — multiset enumeration with multinomial weights. This is the step most generators get wrong; every distribution here is verified against independent brute-force enumeration.Ask the probability panel anything: What are my odds of rolling 15+ on 4d6 drop lowest? → exactly 25/108 ≈ 23.15%. Average damage of a fireball (8d6)? → exactly 28. Use it as a dice roller probability calculator, dice roller odds calculator or dice roller average calculator — every figure on this page is a dice roll probability computed exactly, and the statistics tab doubles as a dice roller statistics and dice roller analyzer view.
Built as a complete dice roller DND players can use for Dungeons & Dragons 5th edition (DND 5e) and older editions:
4d6dl1 — average 12.24, far better than straight 3d6 (10.5).2d20kh1 — average 13.83, crit chance 9.75%.2d20kl1 — average 7.18, crit chance 0.25%.8d6 fireball, 2d6+3 greatsword, 1d12+5 greataxe.10d6, 20d6); the probability panel shows exact hit-count odds.5d6; a fresh Yahtzee is 1/1296 ≈ 0.08%.2d6 with the exact 7-centric distribution chart.d100 percentile rolls.| Feature | This tool (nrtechstudio) | AnyDice | Typical app rollers |
|---|---|---|---|
| Instant notation (no scripting) | ✅ | ❌ (own language) | ⚠️ partial |
| Exact probability | ✅ | ✅ | ❌ |
| Keep highest / drop lowest math | ✅ verified | ✅ | ⚠️ rare |
| Distribution chart | ✅ | ✅ | ❌ |
| Chi-square fairness test | ✅ | ❌ | ❌ |
| 100% client-side / private | ✅ | ❌ (server) | ⚠️ varies |
| Ads / signup | None | None | ⚠️ varies |
Comparison is factual to the best of our knowledge as of October 2026; third-party features may change.
A dice roller is an online tool that simulates rolling dice. You type a dice notation like 3d6 (roll three six-sided dice) and it generates a random result instantly — useful for tabletop RPGs like D&D, board games, and probability experiments.
Exact dice probability is computed with combinatorics, not simulation: plain pools use dynamic-programming convolution, and keep-highest/drop-lowest rolls use multiset enumeration with multinomial weights. This gives mathematically exact probabilities with zero sampling error, unlike Monte Carlo simulation.
4d6dl1 means roll four six-sided dice and drop the lowest one — the standard method for generating D&D ability scores. The average result is about 12.24, and the chance of rolling 15 or higher is exactly 25/108 ≈ 23.15%.
Advantage means rolling 2d20 and keeping the highest (2d20kh1); disadvantage keeps the lowest (2d20kl1). Advantage raises the average d20 roll from 10.5 to 13.825 and nearly doubles the crit chance (5% → 9.75%). Disadvantage lowers the average to 7.175.
kh = keep highest, kl = keep lowest, dl = drop lowest, dh = drop highest, followed by how many dice. So 2d20kh1 keeps the highest of two d20s (advantage), and 8d6dl2 drops the two lowest of eight d6s.
Exploding dice are re-rolled and added whenever they land on their maximum face (written with !, e.g. 2d6!). An exploding d6 averages 4.2 instead of 3.5.
The chi-square goodness-of-fit test compares your recorded rolls against the perfectly uniform distribution a fair die should produce. It outputs a χ² statistic and a p-value: p below 0.05 means the imbalance is statistically significant and the die is likely biased.
Yes. Rolls use the Web Crypto API (crypto.getRandomValues), a cryptographically secure random number generator, with rejection sampling to eliminate modulo bias. Every face of every die has exactly equal probability.
AnyDice is powerful but requires learning its own scripting language and runs server-side with execution limits. This roller accepts standard dice notation directly (2d20kh1, 4d6dl1), and shows the roller, exact probabilities, distribution charts and fairness statistics instantly in one page with no account.
Yes — type d100 or the shorthand d%. Percentile dice are commonly used in systems like Call of Cthulhu for d100 skill checks.
The average of 3d6 is exactly 10.5. Other common averages: 1d20 = 10.5, 2d6 = 7, 1d12 = 6.5, 4d6 drop lowest = 12.24, d20 with advantage = 13.825.
Everything runs 100% in your browser — the page makes zero network requests after loading. Your rolls and statistics never leave your device.
Yes. Any die from d2 to d1000 works — for example d7, d30 or d100. Just type the notation directly. This dice roller supports custom sides on every feature: roller, exact probabilities and fairness testing.
On a single d20 it is exactly 5% (1/20). With advantage (2d20 keep highest) it rises to 39/400 = 9.75%, and with disadvantage it falls to 1/400 = 0.25%.
Yes. Yahtzee uses five d6s — roll 5d6 here. The exact probability panel can also answer classic Yahtzee questions, such as the odds of a Yahtzee (all five matching), which is 1/1296 ≈ 0.08% on a fresh roll.
Completely free, no ads, no signup, no roll limits. It is a single self-contained page that runs entirely in your browser.
Privacy: this tool runs entirely in your browser. No rolls, statistics or personal data are ever sent anywhere.
Free tool by NRTechStudio
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