D&D Dice Notation Explained: The Ultimate Guide to Rolling d4, d6, and d20
You sit down to play your first tabletop RPG session and someone tells you to "roll 3d6 plus your Strength modifier." You nod like you understand. You absolutely do not understand.
This guide fixes that. Here is everything you need to know about how dice notation works in Dungeons and Dragons and virtually every other tabletop system.
What Does the "d" Actually Mean?
The letter "d" simply stands for "die" or "dice," followed by the number of sides on that die. So a d6 is a six-sided cube, a d20 is a twenty-sided icosahedron, and a d4 is a four-sided pyramid. That is the entire vocabulary. Once you internalize that pattern, any notation becomes readable instantly.
The Standard Dice Set
| Die | Sides | Common Use |
|---|---|---|
| d4 | 4 | Dagger damage, magic missile |
| d6 | 6 | Standard damage, ability scores |
| d8 | 8 | Longsword damage, cleric hit die |
| d10 | 10 | Ranger hit die, percentile rolls |
| d12 | 12 | Greataxe damage, barbarian hit die |
| d20 | 20 | Attack rolls, saving throws, ability checks |
| d100 | 100 | Random encounter tables, loot tables |
Reading Dice Notation Step by Step
Dice notation always follows this pattern: [number of dice]d[sides] [modifier].
3d6: Roll three six-sided dice and add the results together. Used for generating character ability scores in older D&D editions.
1d20+5: Roll one twenty-sided die and add five to whatever comes up. This five is typically a skill proficiency bonus or an attribute modifier in 5th edition.
2d8-2: Roll two eight-sided dice, sum them, then subtract two. Common for penalty-heavy damage situations.
4d6, drop the lowest: Roll four six-sided dice, remove the single lowest number, and sum the remaining three. This is the standard ability score generation method in D&D 5e because it slightly biases results toward higher numbers.
Open the Dice Roller
What Is a Nat 20 or a Critical Hit?
In D&D 5e, rolling a natural 20 on a d20 (meaning the die itself shows 20, before any modifiers) is a critical hit on an attack roll. This doubles the number of damage dice you roll. Rolling a natural 1 is a critical failure, meaning you automatically miss regardless of bonuses. These rules only apply to the raw die face result.
Advantage and Disadvantage
D&D 5e introduced a clean mechanic called advantage and disadvantage. When you roll with advantage, you roll 2d20 and keep the higher number. With disadvantage you roll 2d20 and keep the lower. This single rule replaced dozens of situational modifiers from older editions and made the game significantly faster to run.
Practice a Few Rolls Right Now
The best way to internalize all of this is just to roll some dice. Use the virtual dice roller, try a 3d6 for ability scores, try a 1d20 for a perception check, and try 2d8+3 for weapon damage. The notation will click immediately once you see the numbers land.