If you are asking what a monetary value in the past is "worth" today, there is no one correct answer. A price or an income in the past would have been valued in different ways in that time by different people and under different contexts.
are asking about the "present worth" of buying a loaf of bread or filling the gas tank 40 years ago, are you thinking in terms of the amount of money you are spending today on such things? If so, use the price index of the average household called the CPI
. On the other hand, if you are wondering how "affordable" this would be to the average person, use the GDP per capita, or a wage or average earnings index.
I use the site: https://www.measuringworth.com/uscompare/relativevalue.php to calculate the worth
of a given amount in a given year with the worth of that amount in 2016.
In 1931 a certain person earns 2250,00 a year. This income is 50% more then the income of a average person in that year. If you use the CPI (consumer price index) to calculate what
this income would be worth in 2016 then this person would earn 31.500,00. However if you measure the purchasing power of that income in its relative ability to purchase a bundle of goods that a average household would buy 2250,00 in 1931 would mean an income
of 168.000,00 today.
A simple Purchasing Power Calculator would say that the relative value of a camera that in 1935 cost 100,00 cost $1,890.00 in 2022. This answer is obtained by multiplying $100 by the percentage increase in the CPI from 1935 to 2020.
You could also look at the income value of that camera of 100,00. The income value is measured as the mukltiple of average income that would be needed to buy the camera. This measure uses the GDP per capita (measures a country's economic output per person
and is calculated by dividing the GDP of a country by its population).
If you use the income value a camera that cost 100,00 in 1935 would be worth 10.900,00 in 2022. The number of 10.900,00 proves that luxury goods are much much cheaper to day then
in the past. But the second number of 1890,00 gives a better indicating of the relative value of the article to day.