Dice Roller

About Dice Roller

This online dice roller handles all the standard polyhedral dice used in tabletop RPGs and board games - d4, d6, d8, d10, d12, d20, and d100. Pick your die type, set how many to roll (up to 10), choose normal, advantage, or disadvantage mode, and get instant results with visual feedback, roll totals, and a scrollable history of your last 20 rolls. All rolls use the Web Crypto API for cryptographically secure randomness.

Which Dice Are Included?

A standard set of RPG dice contains seven polyhedral dice. This roller covers every type in that set, plus the d100 for percentile rolls.

Die	Faces	Range	Average	Common Use
d4	4	1-4	2.5	Small weapon damage (dagger), minor healing spells
d6	6	1-6	3.5	Board games, fireball damage, ability score generation
d8	8	1-8	4.5	Longsword damage, cleric hit dice
d10	10	1-10	5.5	Paired for percentile rolls, some weapon damage
d12	12	1-12	6.5	Greataxe damage, barbarian hit dice
d20	20	1-20	10.5	Attack rolls, saving throws, ability checks
d100	100	1-100	50.5	Wild magic surges, random encounter tables, loot rolls

The d6 results display classic dot-face icons for a familiar look. Every other die type shows its numeric value in individual result chips so you can see exactly what each die landed on.

How Does Advantage and Disadvantage Work?

In Dungeons and Dragons 5th Edition (including the 2024 revision), advantage and disadvantage are core mechanics that replace most situational modifiers. Instead of adding or subtracting numbers, you roll two d20s and keep one result.

Mode	Mechanic	D&D Examples
Normal	Roll dice as specified, total them	Standard rolls with no special circumstances
Advantage	Roll two dice per die needed, keep the higher	Attacking a prone target, reckless attack, having inspiration
Disadvantage	Roll two dice per die needed, keep the lower	Attacking while blinded, long range attacks, exhaustion levels

The probability impact is significant. On a normal d20 roll, the average result is 10.5. With advantage, the average jumps to 13.825 - roughly equivalent to a +3.3 bonus. With disadvantage, it drops to 7.175, effectively a -3.3 penalty. The effect is strongest in the middle range: if you need to roll between 8 and 14, advantage or disadvantage swings the odds most dramatically. At the extremes (needing a 2 or a 19), the impact shrinks because one roll is almost guaranteed to succeed or fail regardless.

With advantage, rolling a natural 20 happens about 9.75% of the time (roughly 1 in 10 rolls), compared to 5% normally. A natural 1 drops to just 0.25% (1 in 400). Disadvantage flips those numbers - natural 1s become 1 in 10, and natural 20s drop to 1 in 400. In the 2024 D&D rules, advantage and disadvantage still cancel each other out when both apply simultaneously, and multiple sources of advantage do not stack. This roller shows discarded dice crossed out so you can verify which result was kept.

Dice Notation Reference

Tabletop RPGs use a standard notation format called "dice notation" or "NdX notation" to describe rolls. The letter "d" separates the number of dice from the number of faces. Here are common examples with their expected ranges and averages:

Notation	Meaning	Range	Average
1d20	Roll one 20-sided die	1-20	10.5
2d6	Roll two 6-sided dice, sum them	2-12	7
3d8	Roll three 8-sided dice, sum them	3-24	13.5
4d6 drop lowest	Roll four d6, drop the lowest, sum the rest	3-18	12.24
1d12 + 5	Roll one d12 and add 5	6-17	11.5
2d10 (percentile)	Roll two d10 as tens and ones digits	1-100	50.5

The 4d6 drop lowest method is the classic D&D ability score generation technique. Rolling four d6, discarding the lowest, and summing the remaining three gives an average of 12.24 per ability score - about 1.74 points higher than a straight 3d6 roll (average 10.5). This skew toward higher scores is intentional, producing heroes who feel competent rather than average.

Probability and Expected Outcomes

A single die produces a uniform distribution - each face is equally likely. When you roll multiple dice and sum them, the distribution becomes bell-shaped (normal), clustering around the middle values. This is why 2d6 damage feels more consistent than 1d12 damage: both average 7, but 2d6 rolls 6-8 about 44% of the time while 1d12 gives each value only 8.3% probability.

Roll	Chance of Maximum	Chance of Minimum	Most Likely Result
1d6	16.7%	16.7%	All equally likely
2d6	2.8% (rolling 12)	2.8% (rolling 2)	7 (16.7%)
1d20	5%	5%	All equally likely
3d6	0.46% (rolling 18)	0.46% (rolling 3)	10 or 11 (12.5%)
4d6	0.08% (rolling 24)	0.08% (rolling 4)	14 (11.3%)

For a single die, the expected average is (max + 1) / 2. So a d20 averages 10.5, a d6 averages 3.5, and a d12 averages 6.5. When rolling NdX, multiply the single-die average by N. For example, 3d8 averages 4.5 x 3 = 13.5. Knowing these averages helps DMs balance encounters - a spell dealing 8d6 fire damage averages 28 points, while one dealing 3d10 averages 16.5.

A Brief History of Polyhedral Dice

Dice are among the oldest gaming implements in human history. Bone dice dating to around 3000 BCE have been found in archaeological digs across the Middle East and Asia. Ancient twenty-sided dice carved from serpentinite, crystal, and bone - now displayed in museums including the Metropolitan Museum of Art and the Louvre - date from the Ptolemaic period through the Roman era. Their faces were marked with Greek letters rather than numbers.

Modern polyhedral dice owe their RPG popularity to Gary Gygax and TSR. When developing the original Dungeons and Dragons in the early 1970s, Gygax discovered a classroom supplier stocking the five Platonic solid dice (d4, d6, d8, d12, d20). Rather than discarding the non-standard shapes, he designed game mechanics around each one. The 1977 Holmes Basic Set was the first D&D product to include a full set of polyhedral dice in the box. The d10, which is not a Platonic solid, was developed around 1980 to handle percentile rolls more cleanly. Lou Zocchi followed with the 100-sided Zocchihedron in 1985.

The global tabletop RPG market was valued at roughly $2 billion in 2024, with dice and accessories making up a substantial segment. D&D remains the dominant system across the US, Canada, and Australia, which is why the d20 sits at the heart of most dice rollers.

How Random Are Digital Dice?

This roller uses the Web Crypto API (crypto.getRandomValues) rather than Math.random(). The difference matters: Math.random() uses a pseudo-random number generator that can produce predictable sequences if the seed is known. The Web Crypto API draws from the operating system's cryptographic random number generator, which incorporates hardware entropy sources like interrupt timing, mouse movements, and thermal noise. The output is cryptographically secure - suitable for generating encryption keys, not just dice rolls.

One subtlety worth noting is modulo bias. When you take a random 32-bit integer and compute value % max, the result is not perfectly uniform unless max is a power of 2. For example, with a d6, the 4,294,967,296 possible values from a Uint32 do not divide evenly by 6 - four outcomes appear one extra time out of 4.3 billion. In practice, this bias is negligible (less than 0.00000015% skew), far smaller than the manufacturing imperfections in physical dice. For cryptographic applications a rejection sampling approach eliminates this bias entirely, but for dice rolling the difference is unmeasurable.

Roll History and Tracking

Every roll is logged in a scrollable history panel that keeps your last 20 results. Each entry shows the dice type, quantity, mode (normal/advantage/disadvantage), individual kept values, and total sum. This is useful for tracking combat rounds, comparing rolls across turns, or settling disputes about what someone rolled three rounds ago. The history is stored in component state only - it clears when you leave the page, so nothing is saved to your device.

For clearing the history, the tool asks for confirmation before deleting all entries. This prevents accidental loss of roll records mid-session.

Common Dice Rolling Scenarios

Different game situations call for different dice and quantities. Here are worked examples for common D&D 5e situations:

Ability score generation (4d6 drop lowest): Roll 4d6 and get results of 4, 2, 6, 5. Drop the lowest (2), sum the rest: 4 + 6 + 5 = 15. Repeat this six times for all six ability scores. The expected total across all six scores is about 73.44, compared to 63 for a straight 3d6 method.

Attack with a greatsword: Roll 1d20 for the attack roll. If it hits, roll 2d6 for damage (average 7). A critical hit on a natural 20 doubles the damage dice to 4d6 (average 14). With advantage on the attack, your chance of landing that critical rises from 5% to 9.75%.

Fireball spell: Roll 8d6 for damage (range 8-48, average 28). Every creature in the area makes a Dexterity saving throw - roll 1d20 + their Dex modifier against the caster's spell save DC. On a successful save, they take half damage (14 on average).

Percentile roll for Wild Magic Surge: Roll 1d100 (or two d10s). Results range from 01 to 100, with each outcome on the Wild Magic Surge table having equal 1% probability. A roll of 01-02 might trigger a fireball centred on the caster, while 99-00 could grant the ability to fly for the next minute.

Healing with Cure Wounds at 3rd level: Roll 3d8 + spellcasting modifier. With a +4 Wisdom modifier, the range is 7-28 with an average of 17.5 hit points restored.

Need a specific numeric range instead of standard dice? Try the random number generator. For simple heads-or-tails decisions, check out the coin flipper. If you want to calculate the odds of specific outcomes, the probability calculator can help work through the maths. This dice roller runs entirely in your browser with no data sent anywhere.

Sources

• MDN - Crypto.getRandomValues() Web API
• D&D Beyond - Using Ability Scores (Advantage and Disadvantage)
• Wizards of the Coast - D&D 5e System Reference Document v5.1
• Wolfram MathWorld - Dice (probability distributions)
• RFC 4086 - Randomness Requirements for Security