I cannot speak for every country's standard but in Oz the empty & full weights are stamped on the extinguisher.
Just weigh the extinguisher & compare it to those figures.

Same with a BBQ gas bottle, no figures stamped on it but weigh the bottle. Mine is a 9KG cylinder but the weights are
a bit confusing. It weights 9KG empty & 18 KG full.

I use a big extinguisher like turnnburn but made a wheeled stand to make it a little easier to move around. John.