D20 Roller

About the D20 Roller

The d20 is the twenty-sided die at the heart of many tabletop role-playing games. You roll it to see if your hero climbs the wall, hits the dragon or talks past the guard. This page rolls one for you: tap Roll or press the spacebar.

It also does the two things a plain dice app does not: advantage and disadvantage (roll two d20s, keep the higher or the lower) and a modifier that is added to the roll. A natural 20 turns gold and a natural 1 turns red, so nobody misses the big moments.

Features

• One d20, ready — the page opens on a single twenty-sided die
• Advantage and disadvantage — two dice are rolled, the kept one stays bright and the other fades
• Modifier — add or take away up to 30, and the total shows the sum (for example 14 + 5)
• Natural 20 and natural 1 — shown in gold and red, before the modifier is added
• Last rolls — the last 10 results in a row under the dice
• Other dice too — D4, D6, D8, D10 and D12, up to 8 dice at once
• Fullscreen — big dice for the whole table, tap anywhere to roll again
• Saved settings — your roll mode and modifier are remembered in this browser

Advantage and disadvantage

Many games let a hero roll with advantage when things go their way: roll two d20s and keep the higher. When things go badly, they roll with disadvantage and keep the lower. Pick it in Roll mode. The page rolls both dice, keeps the right one and tells you, for example: Kept 17, dropped 5.

Advantage helps more than it looks. The average roll goes from 10.5 to about 13.8, and disadvantage drops it to about 7.2. Here is the chance to roll a target number or higher, before any modifier:

Natural 20 and natural 1

A natural 20 means the die itself shows 20, whatever the modifier is. Many games treat it as a great success, and a natural 1 as a funny failure. On a normal roll each has a 1 in 20 chance (5%).

With advantage, a natural 20 comes up 9.75% of the time, and a natural 1 only 0.25% (both dice must show 1). Disadvantage is the other way round. The page checks the kept die, so a natural 20 that was dropped does not count.

The modifier

In most of these games a check is d20 + modifier: your hero's bonus for strength, skill or luck is added to the roll. Type it in Modifier, for example 5 or −1. The total then shows the sum, such as 19 (14 + 5). Your table's rules decide what number you need to beat — the page only does the rolling and the adding.

Frequently asked questions

Is this d20 fair?

Yes. Each face from 1 to 20 has the same chance, 5%. The roll uses your browser's random numbers; the short spin is only for fun. A real plastic die can be a little uneven — this one is not.

Does the modifier change a natural 20?

No. "Natural" means the number on the die. A 20 with a −2 modifier is still a natural 20 (total 18), and the die still turns gold.

Can I roll several d20s at once?

Yes. Set How many to up to 8 with Roll mode on Normal. Each 20 turns gold and each 1 turns red, and the total adds them all plus the modifier. For advantage or disadvantage the page always rolls exactly two dice.

Can I roll other dice?

Yes. Change Dice type to D4, D6, D8, D10 or D12. Advantage and the modifier work with them too. For a plain dice roller for board games, use the Dice Roller.

Is it for betting games?

No. It is made for tabletop role-playing games, board games and class activities.

Related tools

• Dice Roller — 1 to 8 dice, from D4 to D20, for any game
• Random Number 1 to 20 — the same range as a number, with no repeats
• Coin Flip — heads or tails
• Scoreboard — keep score at the table
• Spin the Wheel — pick a random player or event

How to use it

• Tap Roll or press the spacebar to roll the d20
• Choose Advantage or Disadvantage in Roll mode to roll two and keep one
• Type your bonus in Modifier to see the total
• Look for gold (natural 20) and red (natural 1) on the die
• Press Fullscreen to show big dice to the whole table