How big a dumpster?

[Jean Bolger]

I'm curious to hear if anyone has advice on sizing of a dumpster/dumpsters for an apartment complex. I have finally gotten my property 100% occupied (yay!!) but have also just gotten a complaint letter from the city about the resulting overflowing dumpster (boo!). Is there some rule of thumb for this? Like, say, a 2 yard dumpster equals x number of tenants? 

At this point there is one smaller dumpster on the property, which is 29 one bd units. I don't think I'm having issues with outsiders filling up the dumpsters, since there is city-provided trash service for the surrounding homes. It's probably just the increased use from more tenants.