red onion sets to buy qu

Many of the online retailers sell red onions (red baron or hyred) in units of 250g, for example, without indicating the approx. number of sets in such a unit. Would I be right in thinking it would be about 50 sets roughly. Or nearer 100? Of course I could work it out but cannot for the life of me recall the average weight of a single set! Doh!

thanks

thanks for the info