What does roll a D20 mean?

What is a D20 roll?

A D20 is a die numbered from 1 to 20. Rolling one produces a single face value. For a fair die, each face has the same chance of appearing.

Read a roll with a modifier

The notation 1d20 + 5 means roll one twenty-sided die and add five. If the die shows 14, the total is 19. A modifier changes the total, not the face value.

1d20, 2d20 and D20 + 5 notation

The number before d20 is how many twenty-sided dice you roll. 1d20 + 5 adds five to one die. 2d20 usually means roll two dice and add their faces; it does not mean advantage unless the instruction says to keep the higher die. A percentile D100 roll is a different die, not 100 separate D20 rolls.

In this roller’s batch mode, a modifier applies to each die separately. If two faces are 4 and 17 with +3, their totals are 7 and 20, giving a sum of 27. An instruction to add +3 only once to the summed dice would instead give 24. Read the required convention before using batch totals.

Is an attack roll a D20 Test in D&D?

Yes. In D&D’s 2024 rules, attacks, ability checks and saving throws are D20 Tests. Compare your modified total with Armor Class for an attack, or a Difficulty Class for a check or save. For example, 12 + 3 meets DC 15.

Advantage, disadvantage and common mistakes

In the 2024 D&D rules, multiple sources of advantage still mean two D20s, not three or more. Any combination of advantage and disadvantage cancels to a standard single roll, even when there are more sources of one than the other. Apply the modifier after choosing the kept die.

For faces 4 and 17 with a +3 modifier, advantage produces 20 and disadvantage produces 7. The advantage total of 20 is not a natural 20 because the kept face was 17. Adding both dice would be a different calculation.

Other games and Magic cards can use extra dice differently. Follow their instructions rather than applying D&D’s non-stacking rule; see MTG extra-dice effects.

Do you have to roll a D20 for spells?

Only when the spell calls for it. You roll a D20 for a spell attack; for a saving-throw spell, the target rolls the save. Damage uses the dice specified by the spell. Some spells need no D20 roll.

Do you roll a D20 for stats?

Not for standard D&D ability-score generation. The random method rolls four six-sided dice, drops the lowest and totals the other three, repeating for six scores. Standard array and point buy are alternatives. A D20 ability check uses an existing stat’s modifier; it does not generate the stat.

For example, rolling 6, 4, 3 and 1 gives an ability score of 13 after dropping the 1. Six D20 batch rolls on this site are not a substitute for that method. Use a D20 for character stats only if your game master has agreed to a house rule.

The lowest D20 roll: a natural 1

The lowest face is 1; the highest is 20. “Natural” means before modifiers. On D&D attacks, a natural 1 misses and a natural 20 hits critically. Checks and most saves use the total; death saves have special rules. A natural 1 with +5 still totals 6.

Can you always roll a 20 or roll higher?

No fair technique guarantees a perfect 20 or a high roll every time. Each face has a 5% chance on a standard fair D20. Previous low rolls do not make a high roll due. Advantage improves the odds when your game permits it, but still cannot guarantee success.

How to roll a D20: a practical method

For a physical die, agree on a clear, level rolling area or tray, shake the die and let it tumble to a stop. Read the upward face. Agree beforehand how to handle a die that lands tilted or falls off the table. Consistent handling makes results easy for everyone to read; it is not a way to force higher numbers.

Online, choose the required mode and modifier in the virtual D20 roller, then select Roll D20. Read the raw face and total separately. Choose one accepted rolling method with your group and keep the result rather than rerolling until you like it.

Try it yourself

Roll a D20 online and try a +5 modifier. Then compare standard mode with advantage. See D20 probabilities for the mathematics, or read about D20 rolls in MTG.

Official D&D rules and character creation

These examples use the 2024 rules. The official D&D playing rules explain D20 Tests, attacks and saving throws. For ability-score generation, see creating a D&D character. Your table’s chosen edition and house rules may differ.