Why is the soft level-cap set at level 20, specifically?

Question

I've been wondering lately if there is any sort of precedence or context for the soft level-cap of level 20 in various D20 style tabletop games. I say soft cap because I'd like to, for the purposes of this question, ignore epic-level, mythic-level, gestalt classing, multi-classing, or any other sort of "post-20" play.

The only reason I can think of is a simple relation to the actual 20-sided die and keeping the system semantically linked to this idea, but this is purely speculation. A google search turns up no information.

So, does anyone out there have any historical insight (citation needed!) as to why the level cap for these style games is typically, and specifically, 20? Is it completely arbitrary?

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From Wikipedia:

The term epic level refers to a very high level of play in the Dungeons & Dragons (D&D) fantasy role-playing game. Although such high-level play has existed in various forms in the game for decades, the term "epic level" was introduced in the game's third edition to refer to character levels that are beyond the standard leveling rules, or every level past 20th level. In the case of fourth edition, levels 21 through 30 fall into the Epic Tier level of play. (Emphasis mine)

So why are levels 1-20 standard and anything else beyond that epic? I'm looking for the reason that these numbers, specifically, were set as the limit.

It seems to me that level 20 has historically been the peak level of a player-characters mortal life. Related questions on this site imply ADnD 2nd had a cap of 20, and other sources state that after 3rd Ed., anything after 20th level was considered epic play. (What I mean by "post-20," a term I've seen used elsewhere.)

I'm wondering why the designers chose 20, instead of any other number, as the limit for standard leveling. Or if they even had a real reason at all.

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Some loosely related questions that turned up in search:

• Maximum levels in AD&D 2nd Edition
• What is the purpose of old-school D&D class level limitations?
• Are characters limited to 20th level in 5e?
• Class level vs. Character level vs. “my” level (Pathfinder)

Answer 1

The premise of your question is somewhat incorrect. Level 20 is a standard progression limit only in 3e and 5e.

In First Edition AD&D, there is no level limit. Specific class advancement tables describe advancement from anywhere from 29 levels (cleric) to 9 levels (fighter) but only for purposes of showing how high certain abilities can go, they all note you can go on up infinitely from there. The big differentiation is "name level," which is usually in the 9-10 range, where the character stops getting as large level advances in hp and starts focusing on building kingdoms and whatnot.

In BECMI D&D (Red Box Basic), you can go up to level 36, and there are level breaks from Basic (up to level 3), Expert (up to level 14), Companion (up to level 25), Masters (up to level 36), and Immortal (past that, cashing in XP for power) with differences in those levels of play.

In Second Edition AD&D, advancement is described on convenient charts up to level 20 but there is no limit, with a breakpoint at level 9-10 where you stop getting full hit points with each level. It has a section in the DMG about how play gets harder to be satisfying at higher levels and that you probably need to shift campaign styles. In terms of playstyle recommendation past 20 it says

Consummate skill and creativity are required to construct adventures for extremely powerful characters (at least adventures that consist of more than just throwing bigger and bigger monsters at the nearly unbeatable party). Very high level player characters have so few limitations that every threat must be directed against the same weaknesses. And there are only so many times a DM can kidnap friends and family, steal spell books, or exile powerful lords before it becomes old hat.

It then recommends retirement as an endgame.

In Third Edition D&D, advancement is described up through level 20, with levels past that described in "an upcoming rulebook." It was lightly treated in the DMG but then more fully in the Epic Level Handbook in the 3.5e days. 3.5e and Pathfinder are lightly changed derivatives of 3e by design and so aren't really different editions with different ideas driving them as far as this goes. The Epic Level Handbook describes its intention, which is to change playstyle from the level 1-20 model to being legendary, allowing PCs to "wield powers that other characters (even 20th-level ones) can only dream about." It notes that PCs may have had the thrills of running nations and political machinations come and go and this is their gateway to discovering the secrets of the universe, plugging into the primal cosmic battles, etc. You may also want to review the 3.5e DMG's discussion on epic characters and why attack and save bonuses cap out at 20 on p.207. (Summary: too many attacks causes slog and too much disparity between faster and slower save and BAB progressions causes balance issues). Also on p.210 they explain that many classes have been balanced assuming that 1-20 progression and that balancing classes for infinite progression is way harder.

In Fourth Edition D&D, the level limit is 30. There is no implied "soft cap" at 20. Play is grouped into rough "tiers" from the heroic (1-10) to paragon (11-20) to epic (21-30), but it is a continuum.

In Fifth Edition D&D, the game describes four tiers of play (1-4, 5-10, 11-16, 17-20) with "epic boons" available after level 20.

From this, you can take away several things.

1. The nature of play changes with level. Kicking down the door and killing something works well as a low level adventure and less well as a high level adventure, due to both repetition and the powers and abilities available to higher level PCs and foes, so shifting to more political or grander-scale adventures becomes desirable. Some editions formalize this with tiers, others say "low level, high level, and very high level", etc. What level that is varies by the specific D&D edition and its core rules.

2. There are a variety of "soft caps" and "hard caps" across the editions - tier boundaries, name level, etc. Only in 3e and 5e is 20 specifically a meaningful number that one might describe as a levelling cap (with later progression options). These numbers are not based on some arcane math but on when the designers feel like gameplay breaks down under its prior level paradigm. 4e is reusing the "epic" term but there is a continuum from 1-30 where epic can't be considered a meaningful cap, even a soft one, it's a breakpoint like the one at level 10. It's basically just using previous edition words for that level band to comfort people.

3. "Epic Level" play is a 3e thing based on a very specific product and terminology coined for 3e. Most references you've seen to "post-20 play" and "epic" are just an outgrowth of 3e play specifically. You are seeing something "across all of D&D" which isn't really across all of D&D.

4. Since versions of D&D mostly share certain rule similarities, the breakpoints of power - mostly cemented by what spells become available (fly, teleport, wish, etc. change the dynamics of the game by their availability) tend to be in around the same spots. So short of devising new things (tenth level spells, epic powers, etc.) versions of D&D that use the traditional spell advancement of "a new spell level every couple character levels" cap out spell power right before 20, where then it becomes a game of "more, but not really different" without additional rules that are pointless to include in core books where 99% of people don't ever get up to level 20 anyway. But this means that the around-level-20 breakpoint isn't really deliberately designed, it's more of an inevitable endgame of the spell system, unless you deviate from it (as 4e did). Even in BECMI, the Master rules (level 26-36) are only 32 pages long and are basically some new spells and then siege engine rules. When I played Basic no one ever went past Companion because the game got pretty weird and uninspired there.

5. Given a class-and-level system of D&D's kind, and the kind of Vancian casting powers traditionally available at levels around 5 (fly, fireball), 10 (teleport, raise dead), 18 (wish, miracle) then you get a similar need to change playstyles at those milestones, with 1-5 being your gritty stuff, 6-10 being (super)heroic, above that needing to change more to political and larger scale concerns to keep challenge and interest, and around 20 becoming a point of diminishing returns where you need to do something different to maintain challenge and interest given how spells etc. cap out there. BECMI Master pushed this past to 36 and got boring for that whole range; 4e went to 30 by discarding the Vancian tradition other editions share.

So it is incorrect to say that 20 is a soft cap across most editions, but this is the reason behind it in 3e/5e and the other "caps" and "breakpoints" and "tiers" in other editions in general. It's an emergent condition of the kind of ruleset D&D is and its historical trappings (Vancian magic being the most important) driving a change in playstyles at certain power inflection points. The designers explicitly talk about this in each edition's books regarding high/various level play.

If it needs to be stated more simply, 20 is not a magic number, it's just when having 9th level spells gets old.

Answer 2

OD&D and AD&D (1e) didn't have any specific global limits to level. However, the expectation was that it would take something like 10 years of fairly frequent play to reach 20th level*. Personally, I took that long to reach 13th and some others took a bit less or even more.

However, 20th level was just a marker, not a specific limit. The closest we got to a specific limit in AD&D was the stats in Deities and Demigods, where nothing goes over 30th level, even major gods. It was said in the intro to the earlier "Gods, Demigods, and Heroes" that part of the motivation of giving stats for the gods was to demonstrate the "absurdity" of giveaway campaigns where 40th level characters were running around after just a couple of years play.

Having said that, the game was an ongoing work and when the PHB was written it seems to have been with an expectation of 1.5 million xp being high enough that it would not matter if various classes topped out there. This equates to level 12-17. Obviously, too, demi-human limits in the single digits were not regarded as likely to make the characters unplayable.

UA extended some classes, particularly the druid, beyond this but did not enhance the power level of magic items (staves remaining at 8th level, and rings at 12th for example). Demi-human limits were raised slightly but not as high as 20th.

So, although there was no hard limit, the design of the game was that it regarded 30th level as typical of deities like Odin and even Thor fights as a 20th level fighter, while only artefacts produced effects of higher than 12th level. Player characters were expected to fit into that scale.

Played BtB, of course, AD&D characters are in a setting 99% full of normal people and a 10th level fighter with typical equipment can route an army of those on his/her own (with maybe an application of protection from normal missiles) and is expected to run what is in effect a small country. If the version you're playing is one that gives levels and hit dice to everyone the PCs meet, then the relative power of the PCs is reduced and 10th may not be very powerful.

*This value comes from an article in the last issue of Strategic Review before it became The Dragon. In it, Gygax says that the oldest D&D campaign (Blackmoor) has been running for five years and no one has got past 14th level; so 10 years for 20 is a bit of an extrapolation on my part and maybe a bit high, although EGG is referring there to OD&D which is not quite the same as AD&D. Gygax does say that he would expect that with more than one game per week, (50-75 sessions per year; "session" is not defined but must be at least 4hrs) he would expect 20th to take four or five years. I don't think we ever had a year even as teenagers where we played that many sessions in one year.

On the specific point of the d20 roll, AD&D allowed for negative to-hit requirements so going beyond 20th level was perfectly possible, as were 22d6 fireballs or whatever. Similarly, modifiers can make a skill of over 20 still require a roll. There's no obvious mechanical need to cap at 20 just because of using a d20.

Answer 3

I'm going to tackle this from a different angle and assert that the optimal cap is psychological/sociological and based on player behavior, and that's why even non-DnD RPGs usually use the same max 20 (bonus 30 for hardcore players) cap.

If it turns out that 99.9% of players have no realistic hope of ever reaching max level that renders it meaningless. Level 20 seems to be the sweet spot where no single character overstays its welcome (so people can go and try a new class, new concept), yet you're still able to make lvl 20 abilities attractive, yet keep reaching them in the realm of possibility making them worth struggling for.

When you consider how many months or years a group will stay together in real time, how often they can meet and play (and assume a sizeable enough % of players who stuck around for every campaign or took their characters to their next groups should be able to get rewarded this way). Assuming 1 longer session per week it'd take about 1-2 years to get to level 18 (or 1 year to 10, or 3 months to 6...), which seems to be the expectable human max before people naturally move on with their lives to do something else, or at the very least want to try doing something fresh ( new character, new campaign) in DnD.

That's why the major milestones of each class Path also happen around those levels.

There is really a science to level progression too; there should be enough time given after each ability upgrade for people to ease into using their new powers (and not forget them even though the GM planned the campaign with those solutions in mind, or waste more time learning new rules than actually playing), but should be still frequent enough that the players feel rewarded and motivated to push on.

I think the number 20 is the culmination of all of these factors.