How to use d20/D&D as a resource for GURPS

In many ways, GURPS is a superior system to d20. It is very well supported by many worldbooks (most of which are extremely well researched and written), and is as flexible and open-ended as any rules system needs to be. There are however one or two areas where D&D/d20 beats GURPS hands down.

Adventures and monsters.

Whereas GURPS has emphasised books about worlds and genres, WOTC has pushed published adventures to the forefront. This is unsurprising given how insonsistently the default D&D gameworlds have been treated as the mood takes Wizards of the Coast. Adventures are being created and published at a terrific rate. Between Dungeon Magazine, the free adventures offered at, the download archive, published works and adventures from 3rd party games houses, there’s been no better time to find excellent quality adventures. In comparison, GURPS is positively anorexic in this area.

Similarly, D&D has monsters coming out of it’s proverbial ears. Between the d20 canon, two additional Monster Manuals and the fact every single adventure/guidebook/whatever adds another slew of critters to the pot, D&D must now boast well over 1,000 distinct ways to kill your player characters. There are monsters all the way from the smallest to the all-powerful world eaters. Somewhat impressively, the hit-to-miss ratio is pretty good as well, especially if we discount the awful Monster Manual II from the mix :) In comparison 3rd Edition GURPS had…. well, not a lot. One bestiary, a Fantasy Bestiary, a small section in GURPS Fantasy and a selection of other creatures spread around many worldbooks. There’s perhaps 1/10 of the quantity there is for D&D, and nothing to match the quality.

Both D&D and GURPS provide plenty of assistance when it comes to creating the campaign. With D&D it’s generally a matter of the GM picking one of the published gameworlds (Grayhawk, the Realms, Eberron or whatever) and taking it from there. With GURPS, the campaign world selection is much broader, spanning fantasy, historical, modern and science fiction across multiple genres, but the act of selection is the same. A typical GURPS campaign is more likely to span multiple gameworlds but it’s the initial choice that will provide the foundation for the rest. In either system the GM has the option of creating their own world from scratch as well, and each system offers ample advice for this direction as well.

The problems can start once the campaign begins. A D&D GM gets a lot of help along the way. He has published adventures, monster stats and ideas, plot hooks, free maps to download plus a wealth of background history for each gameworld to fall back on. The GURPS GM has to be much more willing to put the work in to be ready for the next gaming session.

In short: with D&D we have a weak rules system with excellent in-game support. With GURPS we have an excellent rules system but little help for the GM in-game.

This document helps to fix that problem by bringing the two together.

Quite simply, there’s no reason at all why a GM can’t take a group of GURPs players to the Shackled City, through the Tomb of Horrors, and on to Barrier Peak. The GURPs fantasy player can meet Drow, fight Mind Flayers and battle an Umberhulk. All it takes is a little conversion.

What I want to do is create a method of reading D&D stats as GURPS stats so that no conversion is required in advance. Using this system it should be possible for any GM to pick up a d20 adventure module and run it as-is, exactly as if he were running D&D. The net result should be an enjoyable game with good rules, exciting and deadly combat where well rounded characters fight against iconic foes. The best of all fantasy worlds!

Converting Adventures

Getting Started

The first thing to do is to check that a particular adventure is suitable for your level of play. As a guideline, I suggest that a 1st Level character in D&D is roughly equivalent in power to a 4th edition GURPS character built on 50pts + 40pts disadvantages. Add 25 points per D&D Level. This would mean that an adventure suitable for 3rd level characters should be fine for a party of four 100pt (+40pt disads) GURPS characters.

1 D&D level = 50pts + 25pts for each level above 1st (+ 40 pts disadvantages)

This should give a rough idea of the power level of the adventure. Remember to modify the power level according to the number of players – an adventure for four 3rd level characters will be a walk through for six 100pt characters. In this case the adventure would be more suitable for six 75pt characters, or scale the adventure up accordingly.

The Environment

Where a saving throw is required, use the following:

Fortitude = HT
Reflex = Dodge
Will = Will

Modify this by the given DC of the task:

DC 5 – Routine +4 – +5
DC 10 – Easy +1 – +3
DC 15 – Average +0
DC 20 – Hard -1 – -3
DC 25 – Very Hard -4 – -5

For any environmental effects (falling, disease, poison, etc), use the GURPS rules.

Converting Monsters

The goal is to be able to read any D&D statblock and use the numbers for GURPS. This isn’t going to create “stat-accurate” creatures, but it should set the power level close enough for a decent GM to be able to run a game without having to do any pre-work on the module.

We’ll take the iconic Orc as an example:

Orc, 1st-Level Warrior
Medium Humanoid (Orc)
Hit Dice: 1d8+1 (5 hp)
Initiative: +0
Speed: 30 ft. (6 squares)
Armor Class: 13 (+3 studded leather armor), touch 10, flat-footed 13
Base Attack/Grapple: +1/+4
Attack: Falchion +4 melee (2d4+4/18–20) or javelin +1 ranged (1d6+3)
Full Attack: Falchion +4 melee (2d4+4/18–20) or javelin +1 ranged (1d6+3)
Space/Reach: 5 ft./5 ft.
Special Attacks: —
Special Qualities: Darkvision 60 ft., light sensitivity
Saves: Fort +3, Ref +0, Will –2
Abilities: Str 17, Dex 11, Con 12, Int 8, Wis 7, Cha 6
Skills: Listen +1, Spot +1
Feats: Alertness
Challenge Rating: 1/2

Phew! Let’s distill that down to just the stuff you need to look out for in GURPS:

Hit Dice: 1d8+1
Armor Class: 13
Attack: Falchion +4 melee (2d4+4/18–20) or javelin +1 ranged (1d6+3)
Abilities: Str 17, Dex 11, Con 12, Int 8, Wis 7, Cha 6
Skills: Listen +1, Spot +1

There. That’s a little better. What we want is something that means something in GURPS. Special Qualities, etc can be played in game – they don’t need point-for-point conversion. If an Orc has Darkvision and it’s dark then he can see you if it suits the game for him to see you; that’s the joy of being GM :)

The important line is the Abilities line. Every two points above 10 gives a +1 bonus in D&D. This translates straight to a +1 STAT bonus in GURPS. So, D&D STR 16 (a +3 bonus) = ST 13. Taking the revelent stat, this means that this Orc will have

ST 13 DX 10 IQ 9 HT 11

Use CHA, Will, skill levels and any feats that apply as guidelines to adjust Perception and Will from the base IQ level. In this case the Orc has skills that imply Perception should be one higher than IQ, but Will two points lower. Let’s go with that.

Give the Orc combat skills to suit equal to 10 + 1/2 of melee or missile bonus and give damage according to the weapon type. Give DR equal to armor protection, and calculate Dodge, Parry and Block as normal. Add 3 Hit Points for each Hit Die above the first. Calculate Speed as normal, and round up to the next higher number if the creature is particularly fast or has Improved Initiative.

Similarly, give the critter skill levels equal to the stat + 1/2 of the given skill bonus. Again, it’s not spot on accurate, but it’ll suit for the purposes of running a game and providing cannon fodder. Modify any of the numbers by a couple of points to suit.

This Orc will translate to:

Orc, GURPS style
ST 13 DX 10 IQ 9 HT 11
HP 13, Per-10, Will-7
Base Speed: 5.5
DR 2 studded leather
Dodge-8, Parry-9, Block-8
Falchion-12, 2d-1 swing
Javelin-11, 1d thrust

There you have it – one instant Orc!

Most critters can be worked out like this on the fly. The difficult part comes with adjudicating a creature’s special abilities. This is something that can only come with experience – the golden rule being don’t slow up the game.

Have fun!

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