In the movie "Blade Runner", what is the lifespan of the Nexus-6 models?

In the movie "Blade Runner," Nexus-6 models have a lifespan of four years.

The four-year limit is one of the central facts about the replicants hunted in Ridley Scott’s 1982 film. The Nexus-6 generation was engineered by the Tyrell Corporation to be physically powerful, highly intelligent, and nearly indistinguishable from humans, but its deliberately short life expectancy was intended to limit emotional development and make the units easier to control.

Roy Batty and the other escaped replicants are approaching the end of that programmed period when they return to Earth. Roy seeks Eldon Tyrell because he wants more life, while Tyrell explains that extending the lifespan is not possible. This gives the film’s chase a tragic deadline: the fugitives are not simply criminals avoiding capture, but beings trying to survive their built-in expiration.

The answer applies specifically to Nexus-6 models in the original film. It should not be generalized to every replicant in the franchise. Later models, including Nexus-8 units discussed in the wider story, are associated with different lifespan rules.