Comparing the ratings of chess computers to humans has always been tricky because of the single formula used in rating calculators do not allow the calculator to follow the rules of the two formulas required to convert a USCF rating to a FIDE rating or a FIDE rating to a USCF rating. This makes a comparison to USCF or FIDE player ratings very difficult.
The United States Chess Federation (USCF) states in all cases an entry level rating for a beginner as: “Use an initial rating of 750 based on 0 games”.
Even the weakest chess computers know the basic values of each chess piece and as a result avoid giving up a higher valued piece for a lesser valued piece. Therefore it is unlikely for even the very weakest chess computer to be rated below an initial beginner rating of ELO 750 as suggested by USCF with this Beginner start value.
OLD USCF FORMULA TO CONVERT A FIDE RATING TO USCF RATING FOR LESS THAN 2000
USCF = 720 + 0.625*FIDE if FIDE < 2000
The above old rating conversion from FIDE to USCF works as follows, if for example you have a FIDE rating of 1950 ELO:
720+(0.625*1950) = USCF 1939 ELO
You can also by reversing the calculation, use the following formula convert a USCF rating to FIDE:
FIDE = USCF  720 / 0.625
Therefore if for example you start with a USCF rating 1939 ELO and you want to convert it to FIDE you use:
(1939720)/0.625 = FIDE 1950 ELO
Now by using the same above old USCF formula lets try and convert SciSys Mini Chess that is rated by Schachcomputer.Info Active Rating List as ELO 709. Let’s do this with the two assumptions that ELO 709 equals 1) 709 FIDE and 2) 709 USCF:
 720+(0.625*709) = USCF 1163 ELO
 (709720)/0.625 = FIDE  18 ELO
Obviously when you compare the results of this old USCF Formula you see it was not very good at calculating a rating for players in the absolute beginner ranges as in the above examples where a 709 rated USCF player has a FIDE rating of (minus) 18 ELO. Even reversing as in example 2 where the FIDE Rating of ELO 709 equals a USCF rating of 1163 ELO is not very realistic. This old formula was probably never meant to go below converting a 1400 ELO FIDE player to USCF. Which becomes obvious when you realize that FIDE ratings only start at 1400 ELO for Novices. Nothing below 1400 ELO exists for FIDE.
OLD USCF FORMULA TO CONVERT A FIDE RATING TO USCF RATING FOR MORE THAN 2000
USCF = 350 + 1.16*FIDE if FIDE >= 2000
The formula for over 2000 ELO players is a little more realistic. For example a FIDE 2050 ELO player would have:
350+(1.16*2050) = USCF 2028 ELO
However, even this rating was not too accurate as it is generally accepted based on comparing true ratings of players who have both FIDE and USCF that at around the 2000 ELO level a USCF player should be approximately 60 ELO higher. Therefore the 2050 FIDE players should have approximately the equivalent USCF rating of 2110 ELO. Therefore you can quickly see a large discrepancy between 2028 ELO and 2110 ELO of 88 ELO.
