Dice Roller – Roll Dice Online

What Is an Online Dice Roller?

An online dice roller is a free digital tool that rolls virtual dice for you and instantly shows the result. Instead of hunting for a lost d20 under the sofa, you click a button and the roller picks a random number for each die, adds any modifier and shows the total. Our dice roller handles every standard tabletop die — d4, d6, d8, d10, d12, d20 and d100 — plus any custom die from 2 to 1,000 sides, and it can roll up to 50 dice at once.

People use a virtual dice roller for many reasons: playing Dungeons & Dragons or other role-playing games online, settling a board-game dispute, running a classroom probability experiment, picking a random number, or simply because the dice are at home and the game is not. Because every roll runs inside your browser, it works on phones, tablets and computers without any app, download or account.

This page goes further than a simple random dice roll. It includes a dice notation roller that understands formulas such as 2d6+3 and 4d6kh3, a Yahtzee-style game with holds, a D&D toolkit for ability scores and d20 checks, and an odds calculator that draws the exact probability of any roll. Everything is free and your history stays on your own device.

How to Use This Dice Roller (Step by Step)

Everything is organised into six tabs so you can jump straight to what you need.

1. Dice Roller tab. Choose a die (d4 to d100 or a custom number of sides), set how many dice to roll, add an optional modifier and pick a roll mode — plain sum, advantage, disadvantage, or keep/drop the highest or lowest dice. Press Roll Dice or tap the R key on a keyboard. Dropped dice are faded out, maximum rolls glow gold and rolls of 1 glow red.
2. Notation tab. Type a formula such as 2d6+3, 4d6kh3 or 1d20+5 adv and press Enter. You get a per-term breakdown, the total, the possible range and the average roll. Click any example chip for an instant demo.
3. Yahtzee tab. Roll five dice up to three times per turn. Click dice to hold them, and watch the scoring table show what every category would score, with the best option highlighted.
4. D&D Tools tab. Generate a full set of six ability scores, roll a d20 check against a DC with advantage or disadvantage, and roll common spell and weapon damage with one click.
5. Odds tab. Enter any dice formula and see a probability chart, the average, the most likely total and the chance of reaching a target number.
6. History tab. Review your last 50 rolls with simple statistics. History is stored only in your browser.

Dice Types Explained: d4, d6, d8, d10, d12, d20 & d100

A die is named after its number of sides: a d6 has six sides, a d20 has twenty. Each shape produces results from 1 up to its highest face, and every face is equally likely on a fair die. The table below summarises the standard set used in tabletop games.

The average of any die is simply (sides + 1) ÷ 2. That is why a d6 averages 3.5 and a d20 averages 10.5. When you roll several dice, you add the averages together — three d6 average 10.5, the same as one d20, but the spread of results is very different, as the probability section below shows.

What Is a Custom Die?

Not every game uses the standard set. A custom die lets you roll any number of sides from 2 to 1,000. A 2-sided die is a coin flip, a d3 can be simulated with a d6 divided by two, and a d30 or d1000 is handy for random tables, lotteries within a group and classroom activities. Choose Custom in the Dice Roller tab and type the number of sides.

Dice Notation Explained: How to Read 2d6+3

Dice notation is a short way of writing a dice roll that is understood by role-players around the world. The basic pattern is NdS: roll N dice that each have S sides, then add the results.

Keep, Drop, Advantage and Exploding Dice

• Keep highest / lowest (kh, kl): 4d6kh3 rolls four dice and keeps the three highest.
• Drop highest / lowest (dh, dl): 4d6dl1 drops the single lowest die. It gives the same answer as 4d6kh3.
• Advantage and disadvantage: roll two d20 and keep the higher (advantage) or the lower (disadvantage). Written as 2d20kh1 and 2d20kl1 — or simply 1d20 adv in our roller.
• Exploding dice (!): in 3d8! every die that rolls its maximum earns another die, which can also explode. Our roller caps extra dice to keep results sensible.
• Percentile (d%): a d100, often made from two d10 dice read as tens and units.

Dice Notation Examples with Ranges and Averages

Dice Probability: What Are Your Real Odds?

Rolling one fair die gives every face the same chance. Rolling two or more dice and adding them changes everything: middle totals become far more likely than extremes. This is the reason a 7 is the most common result on two six-sided dice, and it explains the shape of the chart below.

There are six ways to make a 7 (1+6, 2+5, 3+4, 4+3, 5+2, 6+1) but only one way to make a 2 or a 12. That is why a 7 appears about one roll in six while double-ones, often nicknamed “snake eyes”, appear about one roll in 36.

The Chance of Rolling at Least One Six

To find the chance of seeing at least one six when rolling n dice, work out the chance of no sixes, which is (5/6) multiplied by itself n times, and subtract it from one.

Notice that even with six dice you are not guaranteed a six — the chance is about 66.5%. Many people expect it to be 100%, which is a classic probability mistake.

Advantage and Disadvantage on a d20

Rolling a d20 twice and keeping the better result sounds like a small bonus, yet it changes the odds dramatically. The table shows the chance of reaching each number or higher with a normal roll, with advantage and with disadvantage.

Dice in D&D and Tabletop RPGs

Tabletop role-playing games use dice to decide whether actions succeed. In Dungeons & Dragons 5th edition the d20 is the main die: you roll it, add a modifier from your character’s ability and skills, and compare the total against a target number such as a Difficulty Class (DC) or an enemy’s Armor Class (AC). Meet or beat the target and you succeed.

Ability Scores: 3d6 vs 4d6 Drop Lowest

Six ability scores define a character. The classic method is to roll 3d6 for each. The most popular modern method rolls 4d6 and drops the lowest die, which produces noticeably stronger characters. Our D&D Tools tab does this for you six times in one click.

With 4d6 drop lowest, an 18 appears about 1.6% of the time compared with roughly 0.46% on 3d6 — more than three times as often.

Ability Modifiers

In D&D 5e the modifier for an ability score is calculated as (score − 10) ÷ 2, rounded down. A score of 10 or 11 gives +0, 14 or 15 gives +2, and 18 or 19 gives +4.

Damage Dice Examples

Different weapons and spells use different dice. Here are some common rolls with their ranges and average damage.

Critical Hits, Natural 20s and Percentile Dice

A natural 20 is a d20 that shows 20 before any modifier. In many games it is a critical success — for attacks, you typically roll the weapon’s damage dice twice. A natural 1 is the opposite and often counts as a miss. Systems such as Call of Cthulhu use percentile dice (d100): you roll under your skill percentage to succeed, so a skill of 60 means a 60% chance.

Dice in Board Games & Classic Dice Games

You do not need a fantasy setting to use a dice roller. Here are some well-known games and the probabilities that make them tick.

Try the Yahtzee tab to feel these odds first-hand: hold the dice you want to keep, re-roll the rest and see how rarely a perfect five-of-a-kind arrives. For a quick game night, the main Dice Roller tab can roll five or six dice in one go with no physical dice needed.

Is This Dice Roller Fair and Random?

Fairness is the first question people ask about any virtual dice. This roller uses your browser’s cryptographically secure random number generator (crypto.getRandomValues) wherever it is available, which is the same kind of randomness used for security tasks. It is far less predictable than the simple pseudo-random functions found in many basic dice scripts.

Avoiding Modulo Bias

A subtle mistake in many online dice rollers is modulo bias. A computer produces a huge random number, and the simplest way to turn it into a 1–6 result is to take the remainder after dividing by six. Because the range of the random number does not divide evenly by six, some faces end up very slightly more likely than others. We avoid this by using rejection sampling: if the random number falls in the uneven leftover part of the range, we discard it and draw again. Every face of every die therefore has exactly the same chance.

Digital Dice vs Physical Dice

Physical dice are never perfect. Tiny differences in weight, rounded edges and the way a die is thrown can introduce small biases, which is why casinos use precision-machined dice. A well-built digital roller can actually be fairer than a cheap set from a toy shop, with the trade-off that you do not get the tactile fun of the throw.

Streaks Are Normal

Random sequences contain streaks. Rolling three sixes in a row happens about once in every 216 sets of three rolls, and nobody should be surprised when it does. The gambler’s fallacy is the belief that a die is “due” for a certain number after a streak — in reality each roll is independent and the odds never change.

Tips for Game Masters, Players and Teachers

For Game Masters

• Keep the Notation tab open for monster damage so you can type 2d8+4 once and re-roll with a single click.
• Use the Odds tab to check whether an encounter is fair — for instance, how likely a goblin is to hit AC 15 with a +4 bonus.
• Roll secretly for hidden checks by using the tool on your own screen while players look at theirs.

For Players

• Use advantage and disadvantage options instead of rolling twice by hand — the roller marks which die counts.
• Check the Odds tab before taking a risky action. A 55% chance feels very different from a 20% chance.
• Generate several sets of ability scores and compare totals against the standard array of 72.

For Teachers and Parents

• Ask students to predict the most common total of two dice, then roll 100 times and compare with the probability chart above.
• Explain expected value by calculating the average of different dice and checking it against the roller’s average tile.
• Use the d100 or a custom die for random selection, group assignment and classroom raffles.

Dice Glossary: Terms Every Roller Should Know

A Short History of Dice and Fun Facts

Dice are among the oldest gaming tools in the world. Cubic dice and their ancestors, such as carved knucklebones, have been found at archaeological sites that are roughly five thousand years old, and dice games were popular in ancient civilisations across Asia, Europe and Africa. The familiar six-sided die has stayed almost unchanged for millennia.

Polyhedral dice — the four-, eight-, ten-, twelve- and twenty-sided shapes — became familiar to modern players through tabletop role-playing games from the 1970s onward, and today a full set is a standard part of any gamer’s bag.

• On a standard six-sided die, opposite faces always add up to 7.
• Rolling double sixes on two dice has a 1 in 36 chance, exactly the same as any other specific pair.
• The word “die” is the singular and “dice” the plural, although many people use “dice” for both.
• A d20 has 20 faces and 30 edges, and is the mathematical shape known as an icosahedron.