BECMI to 5E character levels by class
by Mike HarveyI find that MU spell levels are the most important to overall balance in play, so I use those as a basis in conversion.
BECMI characters are balanced by XP, not level. The Thief hits 36th level and immortality when the fighter is 26th and the MU is 21st and just getting 9th level spells. The XP difference is very important to balance; clerics and MUs gain spells (1st-6th) at the same time, despite an average difference of 3 character levels. At 2,000,000 XP the Thief and Fighter have the same hit points and same Attack bonus; hit points and Attack bonus are both twice as good as a Magic User.
Direct level equivalence for all classes is a fallacy that was implied by TSR modules targeted at a "party level" -- but no party should have matching levels by the time they have 1,000,000 XP, unless the Thief and Cleric are falling seriously behind. The way I think of all this is that Thieves and Clerics have an effective level cap governed by their XP at 36th level.
I would equate 5E levels to MU levels up through 9th, and to MU XP up through 17th level. After 17th level I chose a fixed 480,000 XP per 5E level, since this maps to two fighter levels. To convert a character, lookup the character's XP on the table to find the correct 5E level. The following table shows what this looks like:
| Thf | Clr | Ftr | Dwf | MU | Elf | APL | XP Range | 5E Level |
| 1-2 | 1-2 | 1 | 1 | 1 | 1 | 1 | up to 2,400 | 1 |
| 3 | 3 | 2-3 | 2 | 2 | 1 | 2 | 2,400-5,000 | 2 |
| 4 | 4 | 3-4 | 3 | 3 | 2 | 3 | 5,000-10,000 | 3 |
| 5 | 5 | 4-5 | 4 | 4 | 3 | 4 | 10,000-20,000 | 4 |
| 6 | 6 | 5-6 | 5 | 5 | 4 | 5 | 20,000-40,000 | 5 |
| 7 | 7 | 6-7 | 6 | 6 | 5 | 6 | 40,000-80,000 | 6 |
| 8 | 8 | 7-8 | 7 | 7 | 6 | 7 | 80,000-160,000 | 7 |
| 9-10 | 9 | 8-9 | 8 | 8 | 7 | 8 | 160,000-300,000 | 8 |
| 11-12 | 10 | 9-10 | 9 | 9 | 8 | 10 | 300,000-420,000 | 9 |
| 13-14 | 11-12 | 11-12 | 10 | 10 | 9 | 11 | 420,000-600,000 | 10 |
| 15-18 | 13-15 | 13-14 | 11-12 | 11-12 | 10 | 13 | 600,000-960,000 | 11 |
| 19-22 | 16-19 | 15-16 | * | 13-14 | 11 | 15 | 960,000-1,280,000 | 12 |
| 23-24 | 20-21 | 17-18 | * | 15 | * | 17 | 1,280,000-1,440,000 | 13 |
| 25-28 | 21-23 | 19-21 | * | 16-17 | * | 18 | 1,440,000-1,760,000 | 14 |
| 29-31 | 24-26 | 22-23 | * | 18-19 | * | 20 | 1,760,000-2,000,000 | 15 |
| 32-34 | 27-28 | 24-25 | * | 19-21 | * | 22 | 2,000,000-2,240,000 | 16 |
| 35-36 | 29-30 | 26 | * | 21 | * | 23 | 2,240,000-2,400,000 | 17 |
| * | 31-32 | 27-28 | * | 22-23 | * | 24 | 2,400,000-2,640,000 | 18 |
| * | 33-34 | 29-30 | * | 23-24 | * | 25 | 2,640,000-2,880,000 | 19 |
| * | 35-36 | 31-32 | * | 25-26 | * | 26 | 2,880,000-3,120,000 | 20 |
| * | * | 33-34 | * | 27 | * | 27 | 3,120,000-3,360,000 | 21 |
| * | * | 35-36 | * | 28 | * | 28 | 3,360,000-3,600,000 | 22 |
| * | * | * | * | 29-30 | * | 28 | 3,600,000-3,840,000 | 23 |
| * | * | * | * | 31-32 | * | 28 | 3,840,000-4,080,000 | 24 |
| * | * | * | * | 32-33 | * | 28 | 4,080,000-4,320,000 | 25 |
| * | * | * | * | 34-35 | * | 29 | 4,320,000-4,560,00 | 26 |
| * | * | * | * | 36 | * | 29 | 4,560,000+ | 27 |
APL = average party level (7 characters, one of each class on the table plus an extra fighter), shown for comparison. Asterisks are computed as if max level for the class.
For 5E levels above 20th, assign Epic Boons from DMG page 231. For example, a 30th level MU converts to a level 23 character in 5E, which is a 20th level character with +3 epic boons.
I'm sure a better table could be devised. The table above mainly illustrates the idea of XP equivalence rather than universal level equivalence.
I did take a stab at boiling my table down into formulas, because I couldn't resist. I had to split the 36 level into three segments to get smooth continuity, but got nice simple formulas. I'm a big fan of race-as-class and like to maintain some differentiation so kept classes separate, but it would be easy to collapse these into a single formula if you feel the differences are not worth the complexity.
| Class | 1st-9th | 10th-17th | 18th-36th | 36th is... |
| Thieves | L-1 | L/2+4 | L/4+8 | 17th |
| Clerics** | L-1 | 2xL/5+6 | L/3+8 | 20th |
| Fighters | L | L/3+7 | L/2+4 | 22nd |
| Wizards | L | 2xL/3+3 | L/2+6 | 24th |
| Dwarves, Hobbits, Level | L |
L = BECMI Level **1st level Clerics convert to 1st level Fighters since they have no spells
These tables are an exact match for Cleric and Wizard spell levels, and maintain approximate XP ratio for D&D classes, but are otherwise not reality checked against class abilities.
Example: an 17th level Cleric would be 13th level in 5E (2 x 17 / 5 + 6), able to use 7th level spells.
Note: If you prefer all classes to fit neatly into a 20-level spread, here is a modified version. It also maintains the spell level compatibility for both Cleric and Wizard, but compresses the levels above 21st.
| Class | 1st-9th | 10th-21st | 22nd-36th | 36th is... |
| Thieves | L-1 | L/2+4 | L/3+8 | 20th |
| Clerics** | L-1 | 2xL/5+6 | 2xL/5+6 | 20th |
| Fighters | L | L/3+7 | L/3+8 | 20th |
| Wizards | L | 2xL/3+3 | L/5+13 | 20th |
| Dwarves, Hobbits, Level | L |