As far as I know you cannot compare trees or skills with each other, not even crowns. If Duolingo doesn't provide further information, it's only possible to guess it. I use a table to associate my progresses with levels and use the following data:
1 Crown ~ 35 minutes (actually 20-45, shorter in the beginning, longer for higher levels, only valid for courses with similar average length and 6 lessons per crown)
100 hours of learning is the official (upper) requirement for level A1 according to Cambridge Assessment Institute, which, of course, only can be applied on "real" courses. I set the required value twice (=200h) for my results, since duolingo doesn't provide some contents (free writing etc). This makes round about 346 Crowns, but I wouldn't say, you're level is a clear A1 then, only using Duolingo, without substituting some skills otherwise. If you'd substitute a lot (50:50), you could choose something in the middle as well.