D and D 5e Ability Modifier

D&D 5e Ability Modifiers Explained

In Dungeons & Dragons 5th Edition, each of the six ability scores (Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma) feeds into a modifier. That modifier is what actually gets added to your d20 rolls, your damage, your saving throws, your skill checks. The math behind it is mod = floor((score - 10) / 2). Anything under 10 leaves you with a negative modifier; anything over 10 starts pushing you positive.

A few values worth memorizing: 10 gives +0, 12 gives +1, 14 gives +2, 16 gives +3, 18 gives +4, and 20 lands at +5. Player characters normally cap at 20. Magic items and divine or epic boons can carry a score all the way to 30, which works out to +10. Going the other direction, an 8 gives −1 and a 6 gives −2. You used to see those low scores a lot after the racial penalties of older editions, or when something has been draining your stats.

Applications

Most people reach for this at character creation, then again whenever an Ability Score Improvement comes up (those land at levels 4, 8, 12, 16 and 19), and any time a feat, magic item or spell bumps a score. Tasha's Cauldron of Everything tossed in an optional rule for custom array allocation and floating ancestry bonuses, but even that runs on the exact same modifier formula.

FAQ

Why floor and not round? The Player's Handbook tells you to round down, full stop. That is why 11 is still +0 and 13 is still +1. The half point never matters.

Can I exceed 20? Only with specific magic doing the work for you. Think Tome of Leadership, Manual of Bodily Health, the Belt of Giant Strength, the wish spell, epic boons (DMG p.231), or certain monster stat blocks. Either way, 30 is where it stops.

Does the modifier apply everywhere? Pretty much. Attack rolls, damage when the weapon property lines up (Strength for melee, Dexterity for finesse and ranged), saving throws, and any skill check tied to that ability. It also feeds the derived numbers: AC leans on Dex, HP on Con, your spell save DC on whatever casting stat you use.