JHN 12:3: In this verse the “pound” (RSV; litra in Greek) of costly ointment would have been kept in a relatively small container, something that would hold about a third of a kilogram. This corresponds to the volume of a small jar or tin can today. PV says “half a liter.”
In focus here is not so much the amount of perfume but rather its high value. Translators should ensure that the amount of the ointment chosen to translate this verse would indeed be expensive (about a year’s wages; see the discussion under dēnarion below, Drachma).
It may be most effective to substitute a container for the volume and begin this verse with “Mary took a bottle of very expensive perfume” (GW).
JHN 19:39: RSV understands a litra to be equal to a pound, so at the end of this verse it has “about a hundred pounds’ weight.” This is misleading since the Roman litra contained only about three quarters of a modern pound. For this reason many English translations say “about 75 pounds” (so NIVNCV). In the metric system this will be “about 30 kilos” (FRCL).