Yes, I discovered that as soon as I started using BeerSmith Kevin. I do have my equipment profile set up now, and it makes it obvious that I'll need a larger boil kettle. I've been looking at 15 gal ones since the price difference for the extra 5 gal is minimal. Since I'm using a propane burner (HellFire), I need a triclad bottom: of two 15 gal kettles, one didn't have triclad; the other has a hole for an electric element. (A local shop said they could weld in a SS plug for it for $20 though, so that might be an option.)
For now, I'll settle for 18 litres in a batch.