How many points does priming sugar add?

Like and idiot I added my priming sugar to my beer before I took my FG reading. I was wondering if anyone knows how to calculate how many SG points X number of oz of sugar adds per gallon of beer. I added 3.1oz of corn sugar to ~3.8 gallons of beer, Ended up with a FG of 1.022 which is high but hopefully that is due to the addition of the priming sugar. The OG was 1.072 and it spent 12 days in the primary and 12 in the secondary. Thanks

It would only add about .002, so your real final gravity would be 1.020.

thanks for the reply