On 2021-02-17, NY wrote:
"Jethro_uk" wrote in message
...

But it means a pint weighs a pound - which is vaguely logical

And a litre weighs a kilo ...

Ok pedantry time ...

And, even more important, a cubic centimetre weighs a gramme or a cubic
decimetre (a litre) weighs a kilogramme or a cubic metre weighs a tonne.

.... only when you specify the material, Water, and the temperature
(20C?), and pressure (dunno), and maybe other stuff?