[Post edited to use life expectancy data from estimated time of birth rather than from 2012 and avoid extra significant digits.]
[Edited again to make the title more to the point and less abrasive, change the math since I found that Uganda is not one of their top four countries aided, include an accurate figure for the average age of an AMF beneficiary, link to sources on life expectancy and mosquito net distribution data, and improve some wording.]
This post argues that working a job and donating the resultant money to the Against Malaria Foundation (AMF) is more beneficial than recreation from a utilitarian standpoint.
AMF, GiveWell's current top rated charity, distributes mosquito nets to people at high risk of contracting and dying from malaria. To find the amount of life saved by donating a dollar to AMF, I use the following formula: (average life expectancy in aided country - average age of beneficiary) / dollars AMF needs to save one life.
According to an email from AMF representative Rob Mather, the average age of an AMF beneficiary is 25-30. I'll pick the age 28 to be conservative on the amount of life saved per donation. I made a weighted average by nets distributed of the life expectancies of the top three countries that AMF has worked in (Zambia, Malawi, and Tanzania) to estimate the average life expectancy in a typical AMF-aided country.
Zambia has 332,660 nets distributed, Malawi has 355,400 nets distributed, and Tanzania has 131,293 nets distributed, for a total of 819,353. Zambia has ~41 percent of nets distributed among the top three, while Malawi has ~43 percent and Tanzania has ~16 percent. Zambia's life expectancy for the average 28-year-old beneficiary is 51.56 years, Malawi's is 51.08 years, and Tanzania's is 45.75 years. The average life expectancy for an AMF beneficiary in the top three aided countries multiplies and adds up to ~50.42 years. (Source on life expectancy. Source on net distribution.)
This means that the time saved per life saved is ~22 years. According to GiveWell, AMF needs just under two thousand dollars to save a life. 22 divided by two thousand is ~0.011 years saved per dollar, or ~4.0 days saved per dollar. Suppose that you gave up some recreation time and instead worked some part-time job such as filling out online surveys for five dollars an hour. If each dollar was donated to AMF, that would save ~20 days per hour, or ~480 hours per hour. If the highest-paying job you could work in your recreation time pays five dollars an hour, then to justify your spending time on recreation rather than on working and donating the money to AMF within an altruistic morality, your recreation time would need to be ~480 times as valuable as an equivalent amount of time in a third world person's life. Your recreation time would need to be even more valuable if a higher-paying job was available. Just multiply the available hourly salary by the amount of life AMF can save per dollar to find how much life you can save per hour.
If anyone has more accurate figures, please post them.