Jettisoning Fairings

[The Flying Kerbal]

Not really anything complicated this time guys, just curious really, at what altitude do you pop open those fairings you have so carefully built around that nice new satellite?

As for me, I've never came across anyone really say what height to throw them off; I try to do it at around the 50K mark, but more often than not I forget and end up taking them into space.

[Reactordrone]

If I'm still firing my engines I try to pop them off at about 50-55km to drop some mass. If I've cut my engines I'll let them ride into space.

[DrLicor]

In RSS/RO, I drop them when I've met the 100km mark, Sometimes the first stage burns out before that, so I drop them at a certain point on the second stage. Other times when the first stage goes past the 100km, I drop them right after stage seperation. 
I don't know if you use mechjeb or FAR? In those mods you can get some data of the dynamic pressure, when this reaches zero, it's save to drop them. 

[Superfluous J]

When they stop showing heat effects, which I assume means the payload they're protecting won't have any either. This seems to be somewhere around 60km for my ascents.

By then though I'm almost at orbital velocity so sometimes I just carry them up into space.

[FrostedShoe]

As soon as I am out of the atmo, usually I have solar panels in there so I pop them out at the same time

[ARS]

Generally around 65-70 km altitude when there's no atmospheric drag that'll compromise my payload

[Urses]

My rule of tumb for vanilla is the drag overlay on parts. If fairing has no more drag it is save to drop of and retract all aerohating parts like solars and antennaes.

[Geonovast]

I'm paranoid, so they stay on until 70km.

[Eric S]

Depends on the payload.  If it's not too bad, I might drop the fairing between 40 and 50km.  There's a few craft I've launched with payloads consisting of so many tiny radially mounted parts that even dropping the fairing at 65km resulted in noticeable loss of momentum.  Think of a lander bus with nine landers, each lander consisting of 20-30 parts, for example.

[Foxster]

You have to balance the extra drag of an unshielded payload with reducing the mass by dumping the shell. I've found about 45-50km to be good but it depends on the craft.