A History of Ability Score Modifiers

On the Dungeon World+ Discord, Gojson asked how he could roll up a DW character, rather than just allocating the preset stats.

I suggested he do it old school, rolling 3d6 down the line for each attribute. That may work for you as well, and—if you’re playing a hack that drops ability scores (3-18), as most DW hacks do—then just use the modifiers:

3d6	Modifier
3	-3
4-5	-2
6-8	-1
9-12	0
13-15	+1
16-17	+2
18	+3

The table I listed is from Dungeon World, but you could certainly come up with your own table for house rules.

One community member wanted to know why the ranges were irregular. I pointed out that they were symmetrical:

But the ranges aren’t necessarily intuitive. There are some arbitrary decisions. I pointed out that I might have made 17 or 18 (< 2% chance) a +3, rather than just 18 being a +3.

Jeremy Strandberg responded

IIRC, they chose the ranges they did in order to:

1) throttle how long it took for PCs to get a +3 modifier

2) to match the modifier ranges of one of the earlier D&D editions (B/X, I think?).

Which sent me scurrying for my editions of early D&D. I couldn’t find my physical copy but I had bought the PDF of Holmes Basic (the first Basic D&D, though it was just called Dungeons & Dragons at the time). It was a hodgepodge, without any standard modifiers based on scores, so it definitely wasn’t the source. For instance:

Constitution	18	add 3 to each hit die
	17	add 2 to each hit die
	15-16	add 1 to each hit die
	7-14	no bonus
	6 or less	subtract 1 from each hit die but never less than 1
Dexterity	13 or more	fire any missile +1
	9-12	no bonus
	8 or less	fire any missile -1

Jeremy said, “This prompted me to go looking, and this is the thread I was remembering in which the current stat array was proposed and adopted: Very small tweaks on stat scores.”

Like Holmes Basic, Moldvay Basic also varied by stat, but for STR, CON, and WIS it worked out to: 

3d6 DW	3d6 Moldvay STR, CON, WIS	Modifier
3	3	-3
4-5	4-5	-2
6-8	6-8	-1
9-12	9-12	0
13-15	13-15	+1
16-17	16-17	+2
18	18	+3

As a match for Dungeon World, that may have been the ultimate inspiration. 

In Moldvay, for DEX, it usually worked out like that, except for initiative adjustment.

STR, CON, WIS, DEX (usually)	DEX (initiative), CHA	INT	Modifier
3			-3
4-5	3		-2
6-8	4-8	3-8*	-1
9-12	9-12	9-12	0
13-15	13-17	13-15	+1
16-17	18	16-17	+2
18		18	+3

The reason for “smaller” modifiers for charisma in B/X is that you’re not using it with a d20 but with 2d6; and the dexterity modifier might be used with a single d6 for individual initiative. Arguably leaving strength with up to +3 is weird since it’s used with a single d6 as well when opening doors, but I guess nobody was ever bothered enough by that.

An actually “consistent” approach is to use the standard deviation of the 3d6 roll that generates the ability score. You get what Dan Collins uses (and what I use in my unpublished clone thanks to Dan): 3-5, -2; 6-8, -1; 9-12, +0; 13-15, +1; 16-18, +2; and so on for higher scores. See for example Original Edition Delta [PDF].

His Luminous Preponderancy

But note that 5e, while keeping the consistency across attributes of earlier editions, opted for more granularity.

Ability Scores and Modifiers
1	−5
2–3	−4
4–5	−3
6–7	−2
8–9	−1
10–11	+0
12–13	+1
14–15	+2
16–17	+3
18–19	+4
20–21	+5
22–23	+6
24–25	+7
26–27	+8
28–29	+9
30	+10

The “5e” modifiers with a bonus increase/decrease every two ability scores is in 3e: I believe that’s the first appearance of this scheme.

Yomikoma

See also: Attributes/Stats for Characters in Old School RPGs.

Updated 2024-07-24 with feedback from His Luminous Preponderancy and Yomikoma to the first version of this post.

Photo credit: You can purchase the attribute buttons from WeegonzaBazaar on Etsy.