user20986: When watching The Queen's Gambit I noticed that some players were late to their game. How is time measured in this case?
It is simple when the player playing black is late, because the one playing white would have done their move and switched the clock.
If the player playing white is late - is their clock switched on at the moment the game starts and is let to run?

user12629: It depends. There are two likely sets of rules: FIDE (which governs international events) and USCF (which governs United States events.) These rules differ slightly.
Under FIDE rules, the default time is 0 minutes unless otherwise indicated. This means that, rather than start the clock of a missing White player, Black could simply claim immediate victory if White was late unless the tournament rules specified otherwise. Under USCF rules, the default time is one hour, meaning Black could only claim victory after waiting an hour (unless the clock runs out before then. of course.)
Under either USCF or FIDE rules, if Black is present and the default time is not zero, then Black starts White's clock when the round starts, whether or not White is present.
The USCF also has a different rule than FIDE if both players are late. According to USCF rules:

If both players arrive late, the first to arrive must split the elapsed time before starting the opponent’s clock. For example, if the first player to arrive is 40 minutes late, the clocks should be set to reflect 20 minutes of elapsed time on each side.

But under FIDE rules:

...if neither player is present initially, White shall lose all the time that elapses until he arrives, unless the regulations of an event specify or the arbiter decides otherwise.


user4418: Play starts when the arbiter announces the start of play, usually by saying "Start white's clock". A good arbiter will then walk round the tournament room making sure that all clocks have been started. If both players have yet to arrive at a table then the arbiter will start white's clock. If a black player has not started white's clock then the arbiter will do so and make a mental note to check back and make sure the black player doesn't stop them again as this could lead to the round finishing late.
If a player with the white pieces arrives late, therefore, then when they arrive they will have lost the time from the start of the round when the clocks were started. If the black player was on time then this will be when the black player started the clock. Otherwise it will be when the arbiter started the clock.
If a player with the black pieces arrives late then when they arrive they will have lost the amount of time since clocks were started minus the amount of time white used for the first move.
If the default time is, say, 30 minutes, then the arbiter will go round the room looking for empty seats with a clock with 30 minutes gone. This works for absent white players and for most black players. The exception is when David Howell is white and has taken 10 minutes for his first move.

20986: <p>When watching <a href="https://en.m.wikipedia.org/wiki/The_Queen%27s_Gambit_(miniseries)" rel="noreferrer">The Queen's Gambit</a> I noticed that some players were late to their game. <strong>How is time measured in this case?</strong></p>
<p>It is simple when the player playing black is late, because the one playing white would have done their move and switched the clock.</p>
<p>If the player playing white is late - is their clock switched on at the moment the game starts and is let to run?</p>
 12629: <p>It depends. There are two likely sets of rules: FIDE (which governs international events) and USCF (which governs United States events.) These rules differ slightly.</p>
<p>Under FIDE rules, the default time is 0 minutes unless otherwise indicated. This means that, rather than start the clock of a missing White player, Black could simply claim immediate victory if White was late unless the tournament rules specified otherwise. Under USCF rules, the default time is one hour, meaning Black could only claim victory after waiting an hour (unless the clock runs out before then. of course.)</p>
<p>Under either USCF or FIDE rules, if Black is present and the default time is <em>not</em> zero, then Black starts White's clock when the round starts, whether or not White is present.</p>
<p>The USCF also has a different rule than FIDE if both players are late. According to USCF rules:</p>
<blockquote>
<p>If both players arrive late, the first to arrive must split the elapsed time before starting the opponent’s clock. For example, if the first player to arrive is 40 minutes late, the clocks should be set to reflect 20 minutes of elapsed time on each side.</p>
</blockquote>
<p>But under FIDE rules:</p>
<blockquote>
<p>...if neither player is present initially, White shall lose all the time that elapses until he arrives, unless the regulations of an event specify or the arbiter decides otherwise.</p>
</blockquote>
 4418: <p>Play starts when the arbiter announces the start of play, usually by saying &quot;Start white's clock&quot;. A good arbiter will then walk round the tournament room making sure that all clocks have been started. If both players have yet to arrive at a table then the arbiter will start white's clock. If a black player has not started white's clock then the arbiter will do so and make a mental note to check back and make sure the black player doesn't stop them again as this could lead to the round finishing late.</p>
<p>If a player with the white pieces arrives late, therefore, then when they arrive they will have lost the time from the start of the round when the clocks were started. If the black player was on time then this will be when the black player started the clock. Otherwise it will be when the arbiter started the clock.</p>
<p>If a player with the black pieces arrives late then when they arrive they will have lost the amount of time since clocks were started minus the amount of time white used for the first move.</p>
<p>If the default time is, say, 30 minutes, then the arbiter will go round the room looking for empty seats with a clock with 30 minutes gone. This works for absent white players and for most black players. The exception is when David Howell is white and has taken 10 minutes for his first move.</p>
