5e D&D XP Awards

After playing 5e D&D awhile, I settled on a nice simple metric for XP awards that works for quests & missions, social encounters, and exploration: my guideline XP award per PC is 100 XP per level. That's threat or accomplishment level, which may be the same as PC level but may also be higher or lower. For instance, the awards on the second level of a dungeon will typically be 200 XP/PC, while on the 9th level they'll be 900 per PC. An act worthy of 1st level PCs such as a minor village quest gets 100 XP/PC, while an act worthy of 10th level characters such as victory in a baronial war gets 1000 XP/PC. Saving the world type stuff worthy of 20th level characters gets 2000 XP/PC.

I normally cap any purely social activity awards at 1000 XP per PC per hour of tabletop play, or per 2-3 hours of Internet text-chat play, no matter the PC level, but really major social achievements such as forging an alliance or becoming monarch may get their own awards in addition, again at 100 XP/level per award.

For a 2-3 hour Internet session where things go a bit slowly, a useful guide is to award the standard amount of at least 100 XP per level of each PC, assuming they are actually doing stuff, up to 1000 XP/PC at level 10+.

For a tabletop session I'd recommend three times that a guide to a typical session's total award, ie:

PC Level / Individual Award / Typical Session Award / XP & Sessions to Level

1.        100 / 300  / 300 - 1
2.        200 / 600 / 600 - 1
3.       300  / 900  / 1800 - 2
4.       400 / 1200 / 3800 - 3 or 4 (total 7-8 to 5th)
5.       500 / 1500 / 7500 - 5 
6.       600 / 1800 / 9000 - 5 (total 17-18 to 7th)
7.       700 / 2100 / 11000 - 5 or 6
8.       800 / 2400 / 14000 - 5 or 6
9.      900 / 2700 / 16000 - 5 or 6 (total 32-36 to 9th)
10.     1000 / 3000 / 21000 - 7

Using this metric, a PC can expect to climb from 1st to 11th in around 39-43 sessions of play, somewhat faster than Gygax's '1st to 9th in 50 sessions', but not wildly different, and the main change being the fast levelling up to 4th or 5th level. 

It's ok for awards at low level (1-4) to be somewhat lower, about half the above, but 5e seems to work best with low level PCs advancing at least every 2-3 4 hour (tabletop) sessions, compared to higher level PCs advancing around every 4-6 4 hour sessions, perhaps slower at very high level.

For very high level PCs. 11th+, I don't recommend sticking to a metric by level, the 10th level award of 3000 XP per session serves as a reasonable minimum guide. That gives 5 sessions 11-12 (15000 XP), but at that rate would be 16-17 sessions to go from 19th to 20th.