https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/commercial-lab-surveys.html
OK, now that some seroprevalence survey results are finally available (even though they are at least two months out of date (and not really accurately applicable to current up to date Covid-19 tracking) I'll display how to use them anyway.
total cases = 422,268 total deaths= 32,248
4/01/2020 seroprevalence survey adjustment 12X higher Total Infections = 5,067,216
32.248 deaths / 5,067,216 = IFR (Infection Fatality Rate) 0.63%
total cases = 46,717 total deaths= 4,335
5/03/2020 seroprevalence survey adjustment 6X higher Total Infections = 280,302
4,335 deaths / 280,302 = IFR (Infection Fatality Rate) 1.54%
total cases = 36708 total deaths= 1,359
4/01/2020 seroprevalence survey adjustment 11X higher Total Infections = 403,788
1,359 deaths / 403,788 = IFR (Infection Fatality Rate) 0.33%
total cases = 200,111 total deaths= 3,732
4/10/2020 seroprevalence survey adjustment 11X higher Total Infections = 2,201,221
3,732 deaths / 2,201,221 = IFR (Infection Fatality Rate) 0.17%
total cases = 24,444 total deaths= 1,074
4/26/2020 seroprevalence survey adjustment 24X higher Total Infections = 586,656
1,074 deaths / 586,656 = IFR (Infection Fatality Rate) 0.18%
total cases =24,952 total deaths= 184
5/03/2020 seroprevalence survey adjustment 11X higher Total Infections = 274,472
184 deaths / 274,472 = IFR (Infection Fatality Rate) 0.07%
Just a note to clarify: That was an old survey, over 2 months ago, and during a rapid growth period in the pandemic. A current survey would likely show even more clear definition, with actual current data displaying significantly lower IFRs than those above.