It varies from processor to processor, the new ones take hardly anything, but even the old ones don't take very much - you could always try measuring it, I can't say I've ever bothered!. The biggest current is likely to be the Vpp LED.
I have found that 12v is enof for my processors.
Why is the common 13v and not 12v?
Am I missing something?
The spec from MicroChip is for 12V, but most programmers use 13V as it's usually more reliable - if your 12V rail is only 11.9V it might not work, but if your 13V rail is only 12.9V you've got plenty in hand.
Mine just runs on 2 9V batteries in series, giving 18Volt, wich goes trough an 7815, so i have a VPP of 15V... never had any problems with it and it's much simpler then using special chips to produce 13V
I thought of using that approch.
But I heard they have problems if the batteries aren't a full charge all the time.
So I wanted something portable, simple and compact.