20DDiceRoller

D&D 5e Combat Basics

Everything you need to know about attack rolls, damage, saving throws, and critical hits in Dungeons & Dragons 5th Edition.

The Combat Round

Combat in D&D happens in rounds. Each round, every creature takes a turn in initiative order. A round represents about 6 seconds of in-game time.

On your turn, you can:

  • Move up to your speed
  • • Take one Action (Attack, Cast a Spell, Dash, Dodge, etc.)
  • • Take one Bonus Action (if you have a feature that uses one)
  • • Take one Reaction (opportunity attack, Shield spell, etc.)

Initiative

At the start of combat, everyone rolls initiative: d20 + Dexterity modifier. The highest total goes first. Ties are broken by the DM (often higher DEX modifier goes first).

Making an Attack Roll

To attack, roll a d20 and add your modifiers:

d20 + Ability Modifier + Proficiency Bonus

If the total meets or exceeds the target's Armor Class (AC), the attack hits!

Example:

A Fighter with +5 STR and +3 proficiency bonus attacks an orc (AC 13).
They roll a d20 and get 8: 8 + 5 + 3 = 16. That beats AC 13 — it's a hit!

Damage Rolls

When you hit, roll the weapon's or spell's damage dice and add the relevant ability modifier:

WeaponDamageDie
Dagger1d4 + DEXd4
Shortsword1d6 + DEXd6
Longsword1d8 + STRd8
Greataxe1d12 + STRd12
Greatsword2d6 + STRd6

Critical Hits & Misses

Natural 20 — Critical Hit!

The attack always hits. Double all damage dice (not modifiers). A d8 weapon becomes 2d8 + modifier.

Natural 1 — Critical Miss!

The attack always misses, regardless of modifiers. Some DMs add extra fumble effects.

Saving Throws

Some effects require the target to make a saving throw instead of the attacker rolling to hit. The target rolls d20 + ability modifier + proficiency (if proficient).

d20 + Ability Modifier + Proficiency (if proficient)

If the total meets or exceeds the Spell Save DC, the target resists (usually taking half damage or avoiding the effect entirely).

💡 Quick Reference

Attack: d20 + modifier ≥ AC → Hit → Roll damage
Spell Save: Target rolls d20 + modifier ≥ Save DC → Resists
Crit: Natural 20 = double damage dice
Miss: Natural 1 = always miss