Timing Spells problem

[SRD]

In the PHB I saw that some spells last for 1 round, some for 1 minute, 8 hours, a day etc.
While I know when 1 round ends, I don't know how is the DM supposed to keep track/calculate/decide when does a day/8 hrs/1 min. end.
How is it done? Does the DM just decide when? Or does he roll? and what DC?

Please detail this, as I think time is very underexplained in D&D.

 

[stonegod]

Err.. I'm not sure what you mean.
- A spell that lasts an hour ends 1 hour after you cast it...
- A spell that lasts a day ends 24 hours after you cast it...
Seems straightforward to me.

Edit: In game time, of course (not RL time).

 

[SRD]

What I mean is: HOW do I know 1 hour has passed?
Do I ask the DM every 5 minutes: "Excuse me, DM, has an hour passed already?", "Now is an hour passed?", "Is it now already?".

So: WHO can tell me those things and HOW does he do it?

Example: I just cast Darkvision on me (I'm lvl 3) and it's supposed to last 3 hrs. How can I tell when will it wear off? Does the DM tell me when? And based on what rolls/calculations?

Hope that clears it.

 

[Gilladian]

It really is up to the DM to decide, based on what the PCs are doing.

A three hour spell would last (as far as I'm concerned) through all kinds of combat and exploration, but would have big chunks of its duration eaten up as the PCs search for traps, search rooms for treasure (that can take an hour or more!), etc... and certainly if the party stops for a rest, one could assume the spell's duration was up.

But if the PCs are pushing rapidly through the dungeon, for example, wasting little time on treasure hunting and searching, it could last the whole game session. Or if you're in the city, tracking someone through dark streets, you're pretty much set for a long time.

The thing is, there are rules about how long everything takes. Searching takes so many minutes per so much space, etc... so it is possible to keep quite close track if you want to bother. Most people find that it is better to just go by instinct:

"we stopped and ate lunch, healed joe, and searched the last three rooms, and dismantled the trap outside another door. I think it must have been more than 3 hours..."

Sorry if that's not the answer you were looking for.

 

[SRD]

It is EXACTLY the answer I was looking for. Thanks a lot.

 

[stonegod]

I get it now. It also helps to know about how long skill checks take---if you're taking 20 on a skill that takes a minute, that's eating up 20 minutes at a time.

 

[Delta]

Short answer: The DM tells you when. He's supposed to be keeping track of how long the PC's actions are taking.