Twenty Days of Harvest Work Paid a Year's Rent on Ten Acres
After half the population died, harvest pay rose while land became available.

Institute of Economic Affairs · How The Black Death Increased Worker's Wages: Medieval England's Economic Revolution | IEA InterviewBy 1400 in England, about 20 days of work as a harvest laborer could pay a full year's rent on 10 acres of farmland.
The shift followed the Black Death, which arrived in 1348. Dr. Jordan Clarage, a London School of Economics historian who studies the economy before industrialization, says roughly half the population died, leaving labor scarce while land became available.
Pay for day laborers hired for the harvest roughly doubled between 1348 and 1349. That rise applied only to short term harvest work. Clarage says wages for long term farm workers hired by the year did not rise appreciably until about 1380.
With harvest pay higher and plots available, a peasant could sell labor at harvest time to cover rent and farm a larger plot on better land. But harvest work lasted only six to eight weeks a year, so most families mixed a little wage work with farming their own land.
Questions people ask
How much land is 10 acres, really?
Ten acres is about seven and a half American football fields. For a medieval family it was a viable small farm, large enough to feed a household with grain and leave something to sell, especially once better land became available after the plague.
Could a laborer live year round just by doing harvest work?
No. Harvest work lasted only six to eight weeks a year, so even at high daily rates there were not enough days to live on wages alone. Clarage compares annualizing the rate to assuming a teenager who earns 20 pounds mowing a lawn makes a full time yearly wage at that rate.
Why did wages for year round farm workers take until about 1380 to rise?
They were paid mainly in grain rather than cash. That insulated them from swings in food prices, which mattered when living close to subsistence, but grain was bulky and tied them to one employer for the year.