Pound-for-pound

Sugar Ray Robinson is pound for pound the best boxer ever.

Source: wiktionary

Oakland native Ward is now unbeaten in 25 fights and can now claim to be one of the top few pound-for-pound fighters on the planet after a technically dazzling display.

Source: wiktionary

A tin of tomatoes weighing 250 g and costing $2.50 is more expensive, pound-for-pound, than one weighing 500 g and costing $4 (as the former costs $1.00 per 100 g and the latter $0.80 per 100 g).

Source: wiktionary

My gal is pound for pound sweeter than chocolate.

Source: wiktionary