In one of those idle moments I decided to compare the weights of full and empty cartridges to assess how much ink they really hold. I came up with this. Note these are comparison weights taken on a digital scale, supposedly accurate to 0.1g. Parker Empty 0.9g Full 2.1g Volume 1.2ml Lamy Empty 1.0g Full 2.2g Volume 1.2ml International Empty 0.4g Full 1.2g Volume 0.8ml (Generic) Schmidt Empty 1.9g Full 2.7g Volume 0.8ml Intl converter Diamine Int. Empty 0.4g Full 1.4g Volume 1.0ml In the conversion I have had to assume the mass of ink to be the same as water and the figures should be taken as a comparison rather than absolute. (Maybe someone with laoratory scales would like to continue the "research" What I find interesting is that Parker and Lamy cartridges are perhaps not as big as you thought they were, that the standard converter only holds the same as a standard International cartridge and the "Golden Spot" if you need ink is to carry two Diamine cartridges with a total of 2mls of ink - eyedropper territory without any mess!