How many seconds count until bomb detonates in Counter Strike?

Solution 1:

In most iterations of Counter-Strike by default it is set to 45 seconds. In most competitive and league matches, this value is changed to 35 seconds. Note: that since the Winter update 2015, the bomb timer has been modified to 40 seconds for both Competitive and most league matches.

This can be changed in the console by the server admin with the command:

mp_c4time "[time in seconds]"

in CS:Source and CS:GO the command is:

mp_c4timer "[time in seconds]"

Make sure to wrap time in quotes.

Solution 2:

The time until the bomb im Condition Zero explodes is a server configuration setting by the name mp_c4timer, followed by an integer giving the seconds. According to the Counter-Strike wikia the default server setting is mp_c4timer 45, i.e. 45 seconds.

However, for example the ESL Counter-Strike: Condition Zero 5on5 league rules specify that

mp_c4timer 35

i.e. 35 seconds is to be used.