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Online Dice Roller

Dice Roller

Roll 1 to 20 dice from a d4 to a d100, add a modifier, and see each die and the total right away. Set a target to see the exact chance of reaching it. It is free, works on phone and desktop, and needs no app, install or email.

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How it works

  1. Choose the number of dice (1 to 20), the sides per die (4, 6, 8, 10, 12, 20 or 100), an optional modifier from -100 to 100, and an optional target total. The page opens with one d20 already rolled so you can see how it looks.
  2. Press Roll again. Your browser makes strong random numbers with its built-in crypto.getRandomValues method, described in the W3C Web Cryptography standard. Each number becomes one face from 1 to the number of sides, and every face is equally likely, as a fair die should be. A rare number that would favor some faces is thrown away and drawn again.
  3. The result shows each die in the order it was rolled and the total: all the faces added up, plus the modifier. It also shows the lowest possible total (every die showing 1, plus the modifier) and the highest (every die showing its top face, plus the modifier).
  4. For the odds, the tool counts every possible outcome, which is the number of sides to the power of the number of dice, and finds the share whose total reaches your target. This is the equally likely outcomes rule from the OpenStax Introductory Statistics textbook. The chance is shown as a percent rounded to one decimal place.
  5. Your last 10 rolls are listed on the page so you can look back at them. They stay in this page while it is open and are never saved or sent anywhere.

Questions

Is this dice roller fair?

Each roll uses your browser's crypto.getRandomValues method, which the W3C Web Cryptography standard says makes cryptographically strong random values. The tool maps each number to a face so that every face from 1 to the number of sides is equally likely. Numbers that would tilt the result toward some faces are drawn again.

How is the chance to reach my target worked out?

The tool counts every way the dice can land. Two six-sided dice have 6 times 6, or 36, outcomes. It finds how many of those give a total, with the modifier, at or above your target, and divides by the number of all outcomes. For example, two six-sided dice reach 7 or more in 21 of 36 outcomes, which is 58.3%. One d20 reaches 15 or more in 6 of 20 outcomes, which is 30%.

What does the modifier do?

The modifier is a whole number from -100 to 100 that is added to the dice total, like the +5 a game might give you. It also moves the lowest and highest possible totals. Your target should include the modifier, so if you roll 3d6+2 and need 15, enter 15 as the target.

Why did my roll not match the chance shown?

The chance tells you how often a total comes up over many rolls. As the OpenStax statistics textbook notes, if you roll a die a few times, it is not surprising when the results do not match the probability. A 30% chance can come up three times in a row or not at all for a while.

What happens if my target is very low or very high?

If your target is at or below the lowest possible total, the chance is 100%. If it is above the highest possible total, the chance is 0%. If the chance is above zero but rounds to 0.0, the tool says less than 0.1%.

Can it roll with advantage, exploding dice or custom faces?

No. The tool rolls standard dice numbered from 1 to the number of sides and adds them up. It does not handle advantage or disadvantage, dice that explode or reroll, or dice with custom faces.

Are my rolls saved?

No. The last 10 rolls are listed on the page while it is open. They are not saved and not sent anywhere, and they are gone when you leave or reload the page.

Do I have to give my email?

No. Your roll and the odds show on screen right away. The email box below the result is optional and is there if you want a copy of your roll sent to you.

Sources, checked October 12, 2026