Possibly I'm being downvoted for snark, which is reasonable and I apologise. However I do think I am making an important point, "$400 in 1983 is $1,015.60 in 2018" is basically an innumerate statement. Multiple people make the same mistake in this thread, it seems that people like these inflation calculators and I suppose the fault lies mainly with them for not rounding their output sensibly. $400 in 1983 dollars very (very) roughly corresponds to $1000 of purchasing power today. The dramatic changes in society since 1983 mean that a representative basket of goods has changed dramatically (no Netflix subscription in 1983 for example). So you can only do a very rough calculation. Some things have gotten dramatically cheaper (international travel) some things are barely comparable (advanced healthcare). You somehow have to weigh these things fairly. Basically it's apples versus oranges all the way down. To me "$400 in 1983 is $1,015.60 in 2018" is almost a canonical example of pure and unadulterated nonsense. And yes, I have got a bee in my bonnet on this particular issue :- )

At some point you use the same inflation index everybody else uses.

The problem is not the inflation index: it's quoting approximate numbers with inherently wide error margins with too many digits of precision.

Indeed, thanks. My real beef is with the silly precision but I got distracted explaining (probably unnecessarily) exactly why it can only ever be a very approximate estimate.