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Fatigue & Endurance in GURPS

by Incanus

GURPS Compendium II on page 152 has a detailed elaboration of HT and Hit Points, explaining what happens if for some reason a character has "split" HT stat, ie. if his Hit Points are different than his basic Health. A similar situation can also happen with ST and Fatigue (if the character takes Extra Fatigue advantage, for example, of if the GM uses the Redefining Hit Points and Fatigue optional rule from p. CI7).

Originally, Fatigue in GURPS was meant only as a measure of lowered ST due to physical exertion, and it was easy to track its effects: just subtract the Fatigue from ST and write down the result. However, separating ST from Fatigue has complicated things a bit, and this rules are trying to clarify them again.


Since Fatigue -- and ST under its influence -- is even more fluid stat than Hit Points or Health, we must first define what we're talking about. Although these rules introduce some new terms, these are only new names for old things, to help us avoid the confusion.

Strength (ST): This is one of the four basic character attributes, just as it is described in GURPS Basic Set (p. B13). It is not changed due to Fatigue, and its cost is included in the character's point value. Also, the swing or thrust damage the character can do (p. B74) is based on it.

Effective Strength (eST): This is the "dynamic" counterpart to the basic ST, and for a healthy, rested character it is originally equal to his ST. However, it can change depending on how much Fatigue the character has taken: just subtract Fatigue from the ST to calculate eST.

Endurance (End): This stat represents a character's ability to sustain the physiscal exertion, and is normally based on his ST; however, it can be based on HT if the Redefining Hit Points and Fatigue optional rule (p. CI7) is used, or can be varied with Extra Fatigue and other advantages and disadvantages. Just like ST, it is determined at the character creation and generally stays the same.

Fatigue: As the character exerts himself, he gains Fatigue, which lowers his Effective Strength (see above).


According to the amount of Fatigue the character has taken, there are several effects important in a game. The first and most obvious is the reduction of his physical strength, which is represented with the Effective Strength. However, when the amount of Fatigue taken grows significantly, three other effects come into play: slowing down, collapse and unconsciousness (see p. B134). Those effects appear under the following circumstances:

  1. When Effective Strength reaches one (ie. when Fatigue reaches ST-1), the character slows down (Move is halved, rounding down).

  2. When Effective Strength reaches zero (ie. when Fatigue reaches ST), the character collapses and is unable to do anything physically until he has rested, unless he tries really hard, using the Extra Effort rules below.

  3. When Fatigue reaches Endurance-3, the character slows down as in case #1, above.

  4. When Fatigue reaches Endurance, the character collapses as in case #2 above.

For example, Jennie is a charming Greenpeace activist with ST8 and Endurance 11: she will be slowed down with 7 points of Fatigue and collapse after only 8, but won't fall unconcious until her Fatigue reaches 11. On the other hand, Biff is a car mechanic with ST14 and Endurance of only 11: he will collapse long before his Fatigue could reach his ST.

Extra Effort

Normally, the Extra Effort rules allow a character to do something beond his normal abilities, at the cost of Fatigue. However, this principle can be used with the Fatigue itself, allowing a character to remain active although he have already reached the collapse limit.

In cases #2 and 4 above, the character can remain active -- although at half Move -- if he makes a Will roll for any action that would normally cost him Fatigue. There are two possible effects:

  1. In case #2 above, ie. if the character's eST have reached zero, instead of gaining additional Fatigue Points he loses equal amount of Hit Points.

  2. In case #4 above, ie. when his Fatigue is equal to his Endurance, the character keeps gaining Fatigue points until it reaches the ST level; after that he loses his Hit Points instead, as above.

On a failed Will roll he is unable to do anything. On a Critical Failure he still can't move, but he loses the points as if he had; on a Critical Success he gets to act without any Fatigue or HP loss. All of those Will roles are negatively modified by the amount of Hit Points currently lost.