Level 5: 1350-1425
Level 6: 1600-1675
A small revision to my previous reply:
Level 5: 1375-1425 FIDE
Level 6: 1575-1625 FIDE
Maybe my numbers are too low but I don't think Level 5 is 1700 and Level 6 is 1900.
I barely see any blunders when i play level 6
i guess its different for different people, the levels are not the same for everyone
http://en.lichess.org/vCCnsq8v/white#127that 1 takeback is for checkmate accuracy
i beat it in blitz
http://en.lichess.org/ztmEcxPK/white#105, no takebacks, 1 innaccuracy 2 mistakes, 0 blunders
the extra 3 inaccuracies are checkmate sequence lol
http://en.lichess.org/jyVDztBn/black#1 this was my first 3 min blitz game againts stockfish level 4. Well, it played fast as hell so I lost on time (I also had one takeback because of very retarded mistake).