Bare king rule
He can claim a draw unless the king captured a piece or you played a pawn move in that series. Then the 50M counter is reset.

As Arisktotle said, if no pawn is moved and no piece is captured in 50 moves (50 by each player) then the game is a draw, provided a player claims it as such.
After 75 moves with no Pawn being moved and no piece being taken, an arbiter shall declare the game a draw.
Chess servers usually comply with the '50 move rule' as we know it.
Cheers
Richie
FIDE Instructor-elect, National Arbiter

It is absolutely amazing how everyone ignores the question when they are "answering" it.
"If opponent king is alone and you left with some pieces... "
Are you guys sure that "you can claim a draw" is a reasonable answer to this? I am sure it ain't.

It is absolutely amazing how everyone ignores the question when they are "answering" it.
"If opponent king is alone and you left with some pieces... "
Are you guys sure that "you can claim a draw" is a reasonable answer to this? I am sure it ain't.
It's amazing how you've glossed over his reference to 50 moves.
Assuming that no Pawns have been moved and no pieces captured within those last 50 moves, then:
Yes, "You can claim a draw" is exactly correct.
It is absolutely amazing how everyone ignores the question when they are "answering" it.
"If opponent king is alone and you left with some pieces... "
Are you guys sure that "you can claim a draw" is a reasonable answer to this? I am sure it ain't.
The answer is "nothing happens" because nothing ever happens in chess unless someone "acts" except when some automaticity kick in. It's not only a poorly phrased question, also the situation is poorly defined. There is a massive difference between "no checkmate is possible e.g. when you have 5 same square colored pieces", "you can only mate with the opponents help", "you can only mate with the opponents help but not without reaching the 50-move limit". And that''s not all as there are effects of the 75-move and 5-repeat automatics draws. Also it is most relevant to know who is on move and whether or not a flag has fallen, or anyone needs to plot a survival course in case his flag falls.
So in answering the question, everyone first completes in their mind the situation they believe the OP intended to describe. Frankly I'm not sure and I bet the OP is not sure either. Commonly these questions come from individuals who have poor knowledge of which factors are involved in the termination rules. And so they post incomplete or irrelevant questions.

Frankly I'm not sure and I bet the OP is not sure either. Commonly these questions come from individuals who have poor knowledge of which factors are involved in the termination rules. And so they post incomplete or irrelevant questions.
Yes, exactly. I am pretty sure that at least 2, possibly 3 rules of draw (50-move, insufficient material, possibly even stalemate) are mixed in the OP's head in a chaotic mess. My point is that any answer like "you can claim a draw" will do no good, but will do quite a bit of harm.

If you have mating material but can't deliver mate, you should just find another game to occupy your spare time.
If you have mating material but can't deliver mate, you should just find another game to occupy your spare time.
N&B mate may be difficult for anyone under 1600 so i disagree