Guys I am a MT newbie and how do you tell when a clutch needs to be replaced?

I have 14k km on my ride.
thanks

 

When you put it in fifth on the highway and give it gas and the RPMs move but the car does not.

 

thanks but is that the only way to figure out?
does that affect on 1st to 4th gear lets say in normal driving?

 

The highest gear will slip first. 1-4 will slip eventually, hey you could just leave it in gear and high-rev in your driveway and smell the yummy clutch-burn.

I'd recommend getting a new clutch before that though