How can I convert characters from Basic D&D to D&D 5E?

Question

I've been DM for some adventures using the Holmes Dungeons & Dragons Basic Set (1978 printing), and players created characters using those rules. How would I convert these characters to 5E?

As discussed in this answer, Holmes has very stripped-down rules, no weapon proficiency, no skills, four classes, and a lot of OD&D is still in place. My reason for asking is to take these characters to a local gaming session, since no one is going to use Basic Set rules. Holmes plays very fast compared to AD&D 2E or D&D 5E, so I will need to adjust player expectations.

The characters are 1st through 3rd level depending on how much XP they've earned. It's important to note that the 3rd level cleric in Holmes has only 1st level spells so the character's relative strengths are somewhat different from later editions. Converting XP is another issue since level advancement in Holmes is different from D&D 5E.

Answer 1

There is no direct translation

There are only slim similarities from OD&D and 5eDnD.

• Both use the same ability scores, and in similar range, but the bonuses are very different.
• There are only four classes: "Fighting Men", "Magic-user", "Cleric", and "Thief". These would be similar to "Fighter", "Wizard", "Cleric", and "Rogue", the features and bonuses would be very different.
• There are only four races: Human, Dwarf, Elf, and Halfling. Once again, these can be translated over, but you would need to figure out sub-races for all but human. Each with their own features and bonuses.
• The spells have changed and not all of them have a 5th Ed equivalent.
• There is no concept of Cantrips.
• Magic works differently in general. Before, if you wanted to cast the same spell twice, you'd have to memorise it twice!
• Movement rates have changed: "A fully armoured man can move 120 feet per turn at a cautious walk. Each turn takes ten minutes (scaletime, not actual) in the characters' magical universe." Which means less than 2 ft per round!
  • 120' over 10 minutes becomes
  • 12' (144 inches) over 1 minute (60 seconds)
  • 1 round = 6 seconds
  • Therefore movement is based on 14 inches a round.
• Classes levelled up at different rates, so by the time a Thief has reached level 2, a Magic-user is still level 1-even though they went on the exact same adventure.
• Saving Throws are based on a "thing" not your ability score. So you save against "Magic Wands" and "Death Rays", not Constitution or Charisma.

This list goes on and on.

Basically, the best you could do is:

• Copy over the name of the character
• Copy over the ability scores (raw)
• Translate their race to a newer equivalent and they apply ability score bonuses
• Translate their class to a newer equivalent class
• Verify all their possessions are valid and move them over
• Figure out their current XP (not level) and translate it to the new XP system (magic-users and fighters may go up, and thieves may go down)
• The rest would need to start from scratch (spell books would change, saving throws, bonuses, racial and class features integrated, etc.)

It's not a Herculean task, but it's going to be stripping the current characters down to their foundation and then rebuilding using new rules.