You just take length times width to get square footage. A room 22' x 34' would be 748 square feet.

Thanx Harmany...I just didn't know how it was done lol. I have another question while I'm on the topic of sq. footage. If my area is 748 sq. ft. (that's 2 rms combined) how many btu's in an a/c would I need to cool off both rooms? Would you happen to know? Thanx

carpet may be sold by the sq.ft. but the estimator will figure the job by the sq.yd., your room is 22'wide that could be 2 widths of carpet each 12.0 wide ,so to install the job he will need a 12 x 68.o(2 times 12 x 34 = 12 x 68) or 90.67 sy
you could also do the job with 2 seams ,that would be a 12 x 22.0,3 times or a 12 x 66.0 (88 s.y.)

a good estimator will show you both ways ,do you want 1 seam from top to bottom,or 2 seams from side to side. good luck