Ha ha, that's a bit like asking how long is a piece of string! It varies so much, depending on a number of factors, from the size of the sire and the dam, to her own genetics going back generations, to the quality of the nutrition she got in the first few weeks of her life, to the amount of exercise you give her!
Typically the standard height for adult males is 23 to 25 inches, and females is 21 1/2 to 23 1/2 inches at the withers. This is from the American Boxer Club Standards.
As Honeyec said, weight can vary a great deal. I can give you an average. Females anywhere from 45 - 65 pounds. Males anywhere from 55 - 75 pounds.
My female is 23 inches in height and weighs 62 pounds. She is on the thin side.
My male was 23 inches and weighed 74 pounds.
My friends male boxer was well over 100 pounds. It really just depends on too many factors to give a specific weight.
Hi there, my girl Foxy stayed on the thin side for the first 2 years, we thought something was wrong with her. All checks at the vet said she was right on target. A couple of months ago she started gaining weight and now we call her "Fattie" or "Fat Girl" She just bloomed! I agree, it all depends on the genetics. I hope this was helpful.