What was paul morphys rating. What would his rating be now

Is there a way to calculate that

Yes may be around 2890

Are you assuming that Morphy is allowed an opportunity to learn modern chess?

For any player whose chess career took place before the 1950s-60s, we can only estimate their rating (because official chess ratings were not developed earlier than that).

One method of estimating their playing strength is to take several modern GMs whose games and ratings are well established, run the games through a chess engine to calculate just how accurately these modern GMs played, and use a least-squares curve-fitting algorithm to draw a graph equating CAPS accuracy to rating. Then we similarly analyze the games of the unrated master (eg: Paul Morphy) to obtain a CAPS accuracy score, and use the graph to assign an equivalent rating.

Like this:

Once a genius, always a genius. If Paul Morphy was born in 1990 and felt inclined to make chess his career choice I am sure that he would be ranked among the best players in the world given that he would have access to the latest theory and the help of chess engines.

thanks

http://chessmetrics.com/cm/CM2/PlayerProfile.asp?Params=199510SSSSS3S088959000000111000000000019610100

2700+. Probably would have even surpassed Magnus.   

"... Cons of a CAPS measurement approach are: ..."

https://www.chess.com/article/view/who-was-the-best-world-chess-champion-in-history

Around 950-1400

Or maybe 475

you are trolling

Why this obsession with Morphy?

Maybe ask this person:

"... I memorized every published game morphy played, self analysis, computer analysis and explored dozens of lines for each of them. I could even tell my notes off the cuff. Not to mention having memorized every published game by Smyslov, Botvinnik and Kasparov on that list too. ..." - FvbunNpysUpjlYhjr (~9 days ago)

https://www.chess.com/forum/view/general/im-sorry-but-i-refuse-to-believe-morphy-tal-etc-were-great?page=8

Or this person:

"... I would have had serious chances to beat peak Morphy himself the day I learned how to move the pieces, ..." - YareYareWawa (~4 days ago)

https://www.chess.com/forum/view/general/was-paul-morphys-real-rating-1700?page=3

Anyone seen them lately?

Great point Savage47.

"... My first hero was Paul Morphy. … I think he was just way ahead of his time. I liked his economy. He didn't waste time with his moves: they were very purposeful. In a sense they are classic games: they teach you to attack, not to mess around. … Morphy and I went full circle. He was a hero, then at some stage I thought his games were not very sophisticated and his opponents were bad, and I should look at something better. I now think that he was so much in advance of his contemporaries, just a genius. Some of the ideas were quite deep and he had a fantastic calculating ability. …" - GM Nigel Short (~2016)

still smart and one of the best chess players

I think it’s not only pointless but also disrespectful to evaluate older generation chess prodigies who contributed to chess with little to no theoretical knowledge. Let the legends stay as legends. 

It’s like comparing Newton to present scientists. Present scientists obviously know a lot more than Newton 'cause they have studied everything invented by all other prodigies. 

If you want to compare, then compare it with how many brilliant  novelties one made. How many openings one invented that was not made in the past.

2743
http://chessmetrics.com/cm/CM2/PlayerProfile.asp?Params=199510SSSSS3S088959000000111000000000019610100 

I don't click on links but once a GM title is awarded the player is a GM even if the rating drops (and the direct titles - from doing very well is specified events - allow a player to be a GM with a 2300 ELO).

Thus the phrase "weak GM" (still able to squish most of us like bugs).