The effective altruism movement aims to save lives in the most cost-effective ways. In the future, technology will allow radical life extension, and anyone who survives until that time will gain potentially indefinite life extension. Fighting aging now increases the number of people who will survive until radical life extension becomes possible. We suggest a simple model, where radical life extension is achieved in 2100, the human population is 10 billion, and life expectancy is increased by simple geroprotectors like metformin or nicotinamide mononucleotide by three more years on average, so an additional 750 million people survive until “immortality”. The cost of clinical trials to prove that metformin is a real geroprotector is $65 million. In this simplified case, the price of a life saved is around eight cents, 10 000 times cheaper than saving a life from malaria by providing bed nets. However, fighting aging should not be done in place of fighting existential risks, as they are complementary causes.