Dice Roller
Whether you are playing a board game without the dice, running a Dungeons & Dragons session, teaching probability or settling an argument, this dice roller does the job. Choose how many dice and which kind — from a coin-flip d2 to the percentile d100 — add a modifier, and roll. For d20 systems, the advantage and disadvantage options roll twice and keep the higher or lower result. Every face is equally likely because the roll uses your browser’s cryptographic random generator, and the page also shows the minimum, average and maximum possible so you can see how the dice behave.
How to use the dice roller
- Pick the number of dice and the type of die (d6 is the standard six-sided die).
- Add a modifier such as +3 for a skill bonus, or a negative number for a penalty.
- For D&D-style rolls choose advantage or disadvantage: a d20 is rolled twice and the higher or lower is kept.
- Press Roll. The total, each individual die and the possible range appear.
Formula
A die with s sides gives each value 1…s with probability 1/s. For n dice the average total is n × (s + 1) ÷ 2, the minimum is n and the maximum is n × s. Rolling several dice makes the middle totals more likely than the extremes: with two six-sided dice a total of 7 comes up 6 times in 36, while 2 and 12 come up once each. Advantage raises a d20’s average to about 13.8; disadvantage lowers it to about 7.2.
Worked examples
Two six-sided dice
Roll 2d6: the minimum is 2, the average is 7 and the maximum is 12. Seven is the most common total (6 of 36 combinations); 2 and 12 are the rarest (1 of 36 each).
A d20 attack with a +5 bonus
Set 1 die, d20 and modifier +5. A natural 20 is flagged as a critical hit and a natural 1 as a critical miss. Rolling with advantage means you need both dice to be low to miss — about a 0.25% chance to roll a natural 1 on both.
A percentile roll
Choose d100 for percentage checks, random table results or custom game rules. Each value from 1 to 100 is equally likely.
Common mistakes to avoid
- Assuming dice are “due” for a high number after several low ones. Each roll is independent.
- Forgetting the modifier applies once to the total, not to each die, in most systems.
- Mixing up advantage (keep the higher) and disadvantage (keep the lower).
- Expecting different dice to behave the same. A d20 is flat — every value equally likely — while 2d6 is bell-shaped.
- Using this for gambling decisions where a certified device is required.
Frequently asked questions
Is the dice roller fair?
Yes. Each die is rolled with the browser’s cryptographic random generator, so every face is equally likely.
How does advantage work?
You roll a d20 twice and keep the higher number. Disadvantage keeps the lower.
What is the average roll of 2d6?
Seven. The general formula for n dice with s sides is n × (s + 1) ÷ 2.
What is a d100?
A percentile die that gives a number from 1 to 100, often made from two ten-sided dice.
Can I roll more than one type of die at once?
Roll each type separately and add the totals. This tool rolls one type at a time to keep the odds clear.
Does it store my rolls?
No. Everything runs in your browser.
Sources and further reading
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.