In the heat of combat, the last thing you want to do is pause to look up a a rule. GURPS has detailed weapon statistics that players can write on their character sheets before the game, but sometimes the GM needs to improvise. The PCs accidentally alerted the night watch and you need a polearm’s damage? A character turns a length of rope into a makeshift lasso? When the GM needs to come up with damage numbers on the fly, it can be helpful to make a ballpark estimate of how much damage an attack should generate.
This post provides order-of-magnitude estimates for how much damage weapons do. This is a deliberate oversimplification meant to give GMs guidance when figuring out reasonable estimates: it rounds numbers from the Basic Set, skips over rules in supplement volumes, and doesn’t look at special kinds of damage like armor divisors, fragmentation, and cyclic damage. Using this scale, GMs can choose damage rolls that pass the eyeball test.
Damage Roll Estimates
1d-3: Attacks that deal this level of damage are minor. When relevant, any kind of armor can absorb this magnitude of damage. Any injury that gets through won’t have much effect unless the character is damaged repeatedly.
- Bite (average strength)
- Fire (momentary exposure)
- Poison (mild)
- Punch (average strength)
1d-2: This category is a little more dangerous. Weak armor may not absorb all the damage, but the injury isn’t usually severe on its own.
- Bite (above-average strength)
- Kick (average strength)
- Punch (above-average strength)
1d-1: This level of damage starts to leave an impact. A high roll can take out nearly half of a character’s HP without protection, and multiple hits will quickly accumulate the injury even under the best of circumstances.
- Bow (average strength)
- Fire (sustained exposure)
- Kick (above-average strength)
- Knife (average strength)
1d: Attacks at this level can knock out a normal, unarmored human in two hits! Even a single hit can cripple a limb or cause major injury.
- Bite (extraordinary strength)
- Bow (above-average strength)
- Knife (above-average strength)
- Longbow (average strength)
- Poison (strong, e.g. arsenic)
- Punch (extraordinary strength)
1d+1: Armor is almost mandatory to withstand these attacks. Unprotected characters can expect to lose limbs or collapse from shock.
- Axe (average strength)
- Bow (extraordinary strength)
- Crossbow (average strength)
- Kick (above-average strength)
- Longbow (above-average strength)
- Spear (average strength)
- Sword (average strength)
2d: These attacks can fell an unprotected human in a single blow, and even armored characters will be in trouble if they suffer multiple attacks!
- Axe (above-average strength)
- Crossbow (above-average strength)
- Knife (extraordinary strength)
- Longbow (extraordinary strength)
- Poison (severe, e.g. cobra venom)
- Quarterstaff (average strength)
- Spear (extraordinary strength)
- Sword (above-average strength)
3d: At this level, even basic armor may not be enough to keep a character alive. Unarmored characters will need a great deal of luck to withstand an attack and continue functioning.
- Axe (extraordinary strength)
- Crossbow (extraordinary strength)
- Grenade (powder)
- Machine gun
- Quarterstaff (extraordinary strength)
4d: Unless you are extraordinarily well protected and lucky, your character is out of the battle once one of these blows lands.
- Grenade (fragmentation)
- Laser weapon
- Poison (deadly, e.g. cyanide)
Beyond 4d: Attacks that do more than 4d damage tend to be either superscience weapons, futuristic technology, or weapons designed for heavy targets rather than attacking individuals. You can scale the numbers as large as needed, but it may make more sense to give the weapon an armor divisor or affliction rather than just increasing the numbers.
In the examples above, “average,” “above average,” and “extraordinary” refer to the human norm (specifically ST levels of 10, 12, and 15). It’s not uncommon for realistic animals to reach ST levels of 20, and of course fictional creatures can have far higher strength levels. In those cases, extrapolate as necessary!
The damage rolls were chosen based on the GURPS logarithmic progression. GURPS uses a six step progression in several places, most notably the Size/Speed/Range table, to scale modifiers among several orders of magnitude. The progression goes: 1, 1.5, 2, 3, 5, 7, 10, and then repeats with the new order of magnitude as the base level (so 10*1.5 = 15, 10*2 = 20, etc.). The damage rolls listed yield an average damage that roughly tracks this progression.