I just bought a Skeap digital luggage scale ...not for my bikes per se, but because I'm trying to sell a couple of electric bass guitars and apparently nowadays the first question out of every potential buyer's mouth is "How much does it weigh?"
But since I have this now, I threw a bike on the scale to find out whether I've been guesstimating correctly for all these years.
I have; with pedals, but without pump or saddlebag, the Sachs is exactly 18.75lbs. I've been telling people "it's probably between 18 and 19 pounds" ever since I got it.
$10 on Amazon.