# What's the point of the full move counter in FEN?

For what do you need to know the number of full moves? You still can't recreate every move in the game with FEN anyways, so I don't see the point of the full move counter. Is there any rule that depends on it?

You may want to record a fragment of a real game starting from move number 24, for example. Then you specify the FEN after the first 23 moves and set the full move number to 24.

• Well, that doesn't really explain why it's relevant though. You don't need it to resume the game at that position. Commented Jul 25, 2018 at 9:08
• @Mattias This is the correct answer. The fullmove counter would give the move number, otherwise impossible to recover if the initial position isn't the starting position. Full move counter is common in chess books where the game start from a diagram. You should accept it. Commented Jul 25, 2018 at 10:53

One rule that depends on the move count is the time control. If you have a time control of 40/120, you need to know which move it is to know when the players get more time.

• there's no time control related info in FEN, your explanation does not sound reasonable. Commented Jul 28, 2018 at 2:50
• @lenik Comparing what's in FEN to what's given as required for sealing a move during an adjournment, FEN is missing not only the clock times, but the names of the players, whether there is a pending draw offer, and the date/time/venue. Anyway, I'm just answering the question of "Is there any rule that depends on it?" Time control is probably the only non-obscure rule that depends on the total number of moves played in the game. (Rules stating how many moves can be played at the start of the game before challenging an incorrect starting position count as obscure.)
– D M
Commented Jul 29, 2018 at 5:15
• @DM Threefold repetition is also not covered by FEN :-)
– Marv
Commented Jul 25, 2023 at 18:18