Ability Modifier Calculator
Turn d20-system ability scores into their modifiers and check the point-buy cost of a stat array against your budget. Calculates in your browser.
Modifiers
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Show the math
An ability modifier is how far the score sits above or below the average of 10, in steps of two:
modifier = ⌊(score − 10) / 2⌋
Point-buy costs apply to scores 8–15 (8 = 0 points … 13 = 5, 14 = 7, 15 = 9). Scores outside that range can't be bought.
All math runs locally in your browser.
What this does
An ability modifier calculator turns d20-system ability scores into their modifiers and checks the point-buy cost of a stat array against your budget.
How to use it
- Enter each ability score.
- Read the matching modifier.
- Check the point-buy cost.
- Compare it to your budget.
How it works
So 14 gives +2 and 8 gives −1. Standard point-buy covers scores from 8 to 15.
modifier = (score − 10) ÷ 2, rounded down
Understanding your result
The modifier, not the raw score, is what actually drives every roll, and because it only changes on even scores, a 14 and a 15 give the same plus-2, so an odd score is often wasted points unless something else raises it. Use the point-buy total to keep a custom array within a legal budget rather than quietly building an overpowered character.
Example
A score of 16 gives a +3 modifier.
Sources & methodology
Last updated .
Frequently asked questions
How is an ability modifier worked out?
It is the score minus 10, divided by two and rounded down, so 14 gives +2 and 8 gives -1.
Which scores can point-buy handle?
Standard point-buy covers scores from 8 to 15. Values outside that range have no listed cost.
Is my data kept?
No. Everything is computed locally in your browser.
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