MeasuringWorth is a free online service to calculate relative economic value over time using price indexes.
The site's comparisons over time were used in over 200 academic works each year in 2018 and 2019.
[1] MeasuringWorth.com has calculators offering measures of the price of gold since the year 1257, comparisons of the British pound sterling to the U.S. dollar since 1791, and other "comparators.
"[2][3] Such conversions make implicit assumptions about opportunity costs, and how the potential buyers and sellers would have used their resources given the available alternatives.
[5] The site also hosts essays and academic papers on the subject of long-term comparisons of economic value.