In the 10th volume of The History of Middle-earth (specifically in the "Myths Transformed" essay) it's written that Orcs had short lifespans in relation to the Númenóreans , which would mean that they weren't immortal.
But at least Orcs could live a long life.
The proof for that is Bolg , who died 140 years later than his father, Azog .
Of course it may vary among different breeds of Orcs.
scifi.stackexchange.com/users/13138/Darek Wędrychowski
Orcs seem to have lifespans based on how famous they are.
Azog lived to be at least 319[1], but died through combat at the Battle of the Five Armies.
No definite age is given, only how long he ruled Moria.
Bolg lived to be at least 150[2]
years old.
The Uruk-hai(Saruman Breed) were months/years old.
And some orcs(hinted at, with no evidence) spent their entire lives in Minas Morgul, which spanned several human generations.
And in the behind the scenes(RotK, I think) one of the modelers on the tower made the mention of having orcs live for 100-150 years, then a new set would begin a new set of construction on Barad-dûr[3].
So if you look closely, the CG model of Barad-dûr has a different look all the way up the tower.
In conclusion:Really infamous orc: Possibly 500 years,
at least 319Known orc: 150-200 yearsPeons:
~100 yearsUruk-hai(Saruman Breed): 3-4 years[1]
- Tolkien, The Hobbit, ch. 1: "An Unexpected Party".[2]
- Tolkien, J. R. R. (1937), in Douglas A. Anderson, The Annotated Hobbit,[3] - I am unable to locate an internet source for this bit of information, or an exact time stamp since my DvD player reads 19:99 at anything over 20 minutes.
scifi.stackexchange.com/users/13665/AbeLinkon
Since orcs were a corruption of another race (Maiar, elves, men, depending on which fragment you chose as canon), their lifespan would have been similar to that of that race.
However, the violent culture of the orcs would mean that few "old" orcs would survive.
scifi.stackexchange.com/users/2682/Sardathrion - against SE abuse
The uruk hai probably had life spans similar to men, and there is no indication that they had accelerated aging.
Saruman began his treachery in TA 2759 when he settled at Isengard with the intention of using the Palantir there, and began to fortify Isengard and communicate with Sauron ten years after the Necomancer was driven from Dol Guldur.
This is the most likely time that he started to breed his Uruk Hai, which were a variant of the Black Uruks used by Sauron starting around TA 2475.
It is highly improbable that they were only a few months or years old.
scifi.stackexchange.com/users/25649/StarrySea
Since "myths transformed" are not canon as they where never published, and seemed to be in flux at the time of their writing....
the short answer is no one knows....
however if you ascribe to the common belief of "the wise" of Middle Earth, and Tol Eressëa , Orcs are immortal, and reincarnate after death if possible like the elves whom they where bred from. Since their fea more than likley would not obey the summons to the West...
this could likely explain how they were able to recover so quickly from crushing defeats.
scifi.stackexchange.com/users/47458/user405887
I always thought that once the power of Sauron was finally lifted after the destruction of the ring, the orcs of middle earth gradually changed back to their former selves whether they were elves or men.
I would think that orcs live forever under the influence of Sauron until that point.
scifi.stackexchange.com/users/67878/Andrew J. Gray
The average or expected lifespan of Hobbits, Men and Dwarfs is easily found but I can find no definitive answer for the 'expected' lifespan of an Orc. All I can find so far is, 'unknown'.
How long does the average Orc live?
scifi.stackexchange.com
<tolkiens-legendarium><the-lord-of-the-rings><the-fellowship-of-the-ring>
scifi.stackexchange.com/questions/33986
scifi.stackexchange.com/users/13090/Morgan
Although noone really knows, orcs are said to have lifespans similar to their related races (Maiar, elves, men, etc). Orcs are said to have short lifespans in relation to the  Númenóreans, although it is highly improbable that they were only a few months or years old. It would seem Orcs had a lifespan meaning they are not immortal but there is little information available on their actual lifespan. Since Orcs are a corruption of another race, it is likely their lifespan is mirrored on the lifespan of that race. Furthermore, it is highly improbable they only lived a short time. 
It would seem Orcs had a lifespan meaning they are not immortal but there is little information available on their actual lifespan. Since Orcs are a corruption of another race, it is likely their lifespan is mirrored on the lifespan of that race. It is highly improbable they only lived a short time. 