The bathroom scale before-after technique is how I've weighed my dog (among other things) for years.

"The Neil" is 37 pounds (with empty Topeak MTX rear trunk, not shown), adjustable stem, mini-pump, tube and multi-tool in crotch bag, full plastic fenders, and 1.5 lbs. of Reelight RL770 magnetic induction lights (seen mounted near cassette on rear wheel). Original weight was 25 lbs.