Quoting this from a forum post:
Guild XP is used to level up the guild you are in. Guilds start at level 1 and can move up to level 25 by earning enough Guild XP. The amount of Guild XP required to level up your guild, and the perks you can earn at each level, are listed here:
Whenever you do an activity that qualifies for Guild XP, your current guild will earn that much Guild XP, up to the daily Guild XP cap of 6,246,000. Anything earned after cap is wasted; it does not carry over to the next day.
You can hit the j key (by default) to see your guild information screen, which includes what level your guild is, how much Guild XP has been earned so far today, and what percentage of the cap that is, and the guild's progress towards its next guild level.
The daily Guild XP cap resets at 3am back to 0%. However, there was a known bug (acknowledged by GM tickets) where if someone in your guild earns Guild XP exactly at 3am, the cap may fail to reset. Hot fix notes from January 18, 2011, indicate that this bug is now fixed.
You can right-click on your chat tab and select "Settings" under Filters, then click "Other" and then select the box to show Guild XP gains. (Default color is blue.) Then you'll see a chat line whenever you do something that grants Guild XP.
The following three activities earn Guild XP:
1. Turning in quests -- 25% of the amount of XP you earn is also earned as Guild XP by your guild.
3. PVP in a guild group (rated battlegrounds only) -- see next post.
2. Killing a boss when in a guild group -- see amounts in post after next.
No other activities earn Guild XP. Leveling professions or reputation, archaeology, earning honor, fighting in Tol Barad, clearing trash or mini-bosses in dungeons or raids -- all of that counts for zero Guild XP.
For boss kills, you need a certain number of guild members in your group or raid to get credit as a dungeon group.
* For all 5-person dungeons from vanilla to Cataclysm, you need 3+ guild members (used to be 4+ prior to 4.0.6).
* For all 10-person content (Temple of Ahn'Qiraj [AQ10 formerly AQ20], Karazhan, Zul'Aman, plus all Lich King and Cataclysm raids in 10-person mode), you need 8+ guild members.
* Rated battlegrounds are now (as of 4.0.6) for 10-person pre-formed groups only, and these require 8+ guild members.
* For Burning Crusade 25-person content (Gruul's Lair, Magtheridon's Lair, Serpentshrine Cavern, Mount Hyjal raid, Tempest Keep, Black Temple, and Sunwell Plateau), you need 8+ guild members.
* For Lich King and Cataclysm 25-person content, you need 20+ guild members.
* For classic 40-person content (Molten Core, Blackwing Lair, and Temple of Ahn'Qiraj [AQ40]), you need 10+ guild members.
If you are in a guild group, the icon in the upper left of the mini-map will show your guild crest, and the tooltip will confirm that you are earning Guild XP for boss kills.
(You can also earn Guild Achievements, such as for completing the dungeon or raid the first time. Note that for guild achievements, you only need to kill the final boss while in a guild group. Party members don't even have to engage or tap the final boss -- as long as they're in the instance, you'll get the achievement when the last boss is killed if you're in a guild group.)
The reputation level of a guild member is irrelevant, nor does it matter if they've been in the guild for a day or a year. There are no individual caps that prevent a person from continuing to earn Guild XP or contributing to guild groups -- the only cap that matters is the daily Guild XP cap. So even if a guild member has maximized their guild rep for the week, they can still earn Guild XP.
If you are not in a guild group, you will earn zero Guild XP, zero guild rep, and cannot earn Guild Achievements.
Note that party/raid members do NOT need to engage, tap, or kill the boss in order to earn Guild XP. So you can have two people duo Molten Core, for example, with 8 more guild members AFK by the door. All ten members will still earn Guild XP.
Dungeon boss kills award the following amount of Guild XP, per person in the party:
If you are in a group with five guild members: (125% awarded)
46,500 Heroic boss -- all 9 Cataclysm heroics
31,000 Normal 85 boss -- Grim Batol, Lost City, Halls of Origination
22,750 Normal 81-84 boss -- Stonecore, Vortex Pinnacle
14,250 Normal 80-81 boss -- Blackrock Caverns, Throne of the Tides
If you are in a group with four guild members: (100% awarded)
37,200 Heroic boss -- all 9 Cataclysm heroics
24,800 Normal 85 boss -- Grim Batol, Lost City, Halls of Origination
18,200 Normal 81-84 boss -- Stonecore, Vortex Pinnacle
11,400 Normal 80-81 boss -- Blackrock Caverns, Throne of the Tides
If you are in a group with three guild members: (50% awarded)
18,600 Heroic boss -- all 9 Cataclysm heroics
12,400 Normal 85 boss -- Grim Batol, Lost City, Halls of Origination
9,100 Normal 81-84 boss -- Stonecore, Vortex Pinnacle
5,700 Normal 80-81 boss -- Blackrock Caverns, Throne of the Tides
(Note that prior to 4.0.6, there was no difference between the Guild XP awarded to a four person group versus a five person group, and three person groups could not earn Guild XP at all.)
* For a five person group, each heroic dungeon boss kill is a total of 232.5k Guild XP (46.5k per person). That 232.5k total is 3.7% of the Guild XP cap. That means the five-person group needs to make 26.9 total heroic boss kills per day to hit the Guild XP cap.
* For a four person group, it's 148.8k Guild XP total per heroic dungeon boss kill. That's 2.4% of the cap. The four-person group needs to kill 42 heroic bosses to hit cap.
* For a three person group, it's 55.8k Guild XP total per heroic dungeon boss kill. That's 0.9% of the cap. The three-person group must kill 111.9 heroic bosses to hit cap.
(Remember, as far as Guild XP goes: Trash awards nothing. Completion awards nothing. It's just boss kills that count, and only if you're in a group that has 3, 4, or 5 guild members.)
That means that heroic runs can really vary in terms of Guild XP awarded, depending on the number of guild members and number of bosses. Here are some examples:
* Worst case: Heroic Vortex Pinnacle (3 bosses), with 3 guild members: 167.4k guild XP, 2.7% of cap (37.3 runs required in a day to hit cap).
* Best case: Heroic Halls of Origination (7 bosses), with 5 guild members: 1,627.5k guild XP, 26.1% of cap (3.8 runs required in a day to hit cap).
* Middle case: Heroic Grim Batol (4 bosses), with 4 guild members: 595.2k guild XP, 9.5% of cap (10.5 runs required in a day to hit cap).
Heroic boss kills are worth a lot more than boss kills from normal dungeons (it's a 50% bonus over a level 85 boss on normal). But, running a 5-guildmember normal is generally worth more than a 3-person run of a heroic.
Take, for example, Normal Blackrock Caverns. With 5 bosses at 11.4k each, that's 228k Guild XP earned if it's a 4-person run, or 3.7% of the cap in total. For a 5-person run, it's 356.3k Guild XP, or 5.7% of the cap. That's worth more than any 3-person heroic except Heroic Halls of Origination. However, it would take 27.4 runs of 4-person Normal Blackrock Caverns in a day to hit cap, or 17.5 runs for 5-person. That's a lot of runs!
Here's a rundown of each dungeon, and what percentage of the cap is earned:
Three guild member runs:
6.3% Heroic Halls of Origination (7 bosses)
5.4% Heroic Deadmines (6 bosses)
4.5% Heroic Blackrock Caverns (5 bosses)
4.5% Heroic Shadowfang Keep (5 bosses)
4.2% Normal Halls of Origination (7 bosses)
3.6% Heroic Grim Batol (4 bosses)
3.6% Heroic Lost City (4 bosses)
3.6% Heroic Stonecore (4 bosses)
3.6% Heroic Throne of Tides (4 bosses)
2.7% Heroic Vortex Pinnacle (3 bosses)
2.4% Normal Grim Batol (4 bosses)
2.4% Normal Lost City (4 bosses)
1.7% Normal Stonecore (4 bosses)
1.4% Normal Blackrock (5 bosses)
1.3% Normal Vortex Pinnacle (3 bosses)
1.1% Normal Throne of Tides (4 bosses)
Four guild member runs:
16.7% Heroic Halls of Origination (7 bosses)
14.3% Heroic Deadmines (6 bosses)
11.9% Heroic Blackrock Caverns (5 bosses)
11.9% Heroic Shadowfang Keep (5 bosses)
11.1% Normal Halls of Origination (7 bosses)
9.5% Heroic Grim Batol (4 bosses)
9.5% Heroic Lost City (4 bosses)
9.5% Heroic Stonecore (4 bosses)
9.5% Heroic Throne of Tides (4 bosses)
7.1% Heroic Vortex Pinnacle (3 bosses)
6.4% Normal Grim Batol (4 bosses)
6.4% Normal Lost City (4 bosses)
4.7% Normal Stonecore (4 bosses)
3.7% Normal Blackrock (5 bosses)
3.5% Normal Vortex Pinnacle (3 bosses)
2.9% Normal Throne of Tides (4 bosses)
Five guild member runs:
26.1% Heroic Halls of Origination (7 bosses)
22.3% Heroic Deadmines (6 bosses)
18.6% Heroic Blackrock Caverns (5 bosses)
18.6% Heroic Shadowfang Keep (5 bosses)
17.4% Normal Halls of Origination (7 bosses)
14.9% Heroic Grim Batol (4 bosses)
14.9% Heroic Lost City (4 bosses)
14.9% Heroic Stonecore (4 bosses)
14.9% Heroic Throne of Tides (4 bosses)
11.2% Heroic Vortex Pinnacle (3 bosses)
9.9% Normal Grim Batol (4 bosses)
9.9% Normal Lost City (4 bosses)
7.3% Normal Stonecore (4 bosses)
5.7% Normal Blackrock (5 bosses)
5.5% Normal Vortex Pinnacle (3 bosses)
3.4% Normal Throne of Tides (4 bosses)
Each Cataclysm raid boss is worth 78,700 Guild XP per person. (Prior to a hot fix implemented on Tuesday, February 22, it was 25,700 Guild XP per person.)
For a guild run of 10 people, that's 787,000 Guild XP per boss, or 12.6% of the daily Guild XP cap, meaning you'd need to kill 8 bosses in a single day to hit cap just from Cataclysm raiding.
(Heroic bosses may be worth more? Need to check. If you have info, please provide.)
(I haven't confirmed it's the same in 25-person mode.)
For a guild run of 25 people, that's 1,967,500 Guild XP per boss, or 31.5% of the daily Guild XP cap, meaning you'd need to kill a bit more than 3 bosses in a single day to hit cap just from Cataclysm raiding.
Older Dungeon/Heroic/Raid Content:
More data needed for dungeon and raid boss kills. Please contribute!
Blackfathom Depths (4 person group):
650 for Gamaroo
665 for Twilight Lord Kelris / Aku'mai / Old Serra'kis
Blackrock Depths (4 person group):
2725 Ambassador Flamelosh and 7 dwarves
2815 Magnus and Emperor Dagran Thaurissa
BC raid bosses (Kara, Zul'Aman, Gruuls, Mags, SSC, TK, BT, Sunwell) award 6,835 Guild XP per character per boss. With 10 toons, that's 68,350 rep, or 1.1% of the daily guild XP cap.
BC Dungeons: Heroic Ramparts/Blood Furnace/Shattered Halls (4-person): 10,148 guild rep per guild member, or 12,685 for 5-person. (For some reason, the fFirst boss of Blood Furnace gave slightly less --12,562.)
More data needed for BC dungeon bosses on normal and heroic.
Normal boss kills in Trial of Champions dungeon (4 person group):
7,350 guild xp per player (plus 18 guild rep, 5 honor points)
Heroic boss kills in Trial of Champions dungeon (4 person group):
17,400 guild xp per player (plus 42 guild rep, 6 honor points, 1 Champion's Seal)
Normal dungeons per boss kill for other LK dungeons
Heroic dungeons per boss kill for other LK dungeons
For 10-person raids (such as Sartharion, and the four bosses in Wintergrasp), the boss kill awards 14,600 guild rep. For a full group of 10, that's 146k guild rep, or 2.3% of the Guild XP cap. Killing 42 LK raid bosses in a day would be enough to complete the daily Guild XP cap.
(To be determined: 25-person boss kills award the same amount? Heroic also? How much will this increase after Tuesday?)
Cataclysm Daily Quests:
Dailies offer the following Guild XP values (which is just the personal XP divided by 4):
17,350 Cooking, Fishing, Jewelcrafting, & Tol Barad dailies
13,800 Twilight Highland dailies
13,725 Deepholm: Glop, Son of Glop or The Restless Brood
10,975 Deepholm: All other dailies
10,975 Ramkehan daily: Fire in the Sky
8,238 Ramkehan daily: Thieving Little Pluckers
Lich King Daily Quests:
17,350 Dalaran Fishing daily
13,012 Dalaran Cooking daily
5,512 Typical level 80 dailies such as King of the Mountain, Argent Tourney dailies, etc.
Note that the Dalaran fishing daily is worth exactly as much as the Orgrimmar/Stormwind fishing daily.
The "best case" for doing 25 dailies is to manage to hit all 18 TB dailies (waiting for the respawn so you get all 12 that are possible in the contested area, plus the 6 on the TB Peninsula), plus 3 cooking and fishing dailies (that is, Dalaran fishing, plus your home city's fishing/cooking), and 4 Twilight Highlands dailies. That is 420k Guild XP, or 6.8% of the daily cap. It would then take 15 people doing exactly that in order to hit the cap for the day.
If you did the home city cooking, fishing, 12 TB dailies (assuming you don't get all 18 that are possible if you wait for respawn), 7 Deepholm dailies, and 4 of the 5 Twilight Highlands dailies, that's 377,675 total guild XP earned, or a bit more than 6% of the cap. It would then take 16.5 people doing all 25 of their dailies in this way in order to hit cap each day.
A more realistic scenario (but still a lot of effort) is to do cooking, fishing, 12 TB dailies, and then Glop + Pebble (if they're available). That's 267.6k XP, or 4.3% of the daily cap, meaning that if 23.3 active players did that, the guild would hit cap.
Of course regular quests give XP as well -- 25% of the amount you earn for your character (whether 85 or not) gets awarded to the guild. Typical quests in Mt. Hyjal for example award 27.7k XP, or 6,925 towards the cap. Typical quests in Twilight Highlands award 55.5k XP, or 13.8k towards the cap.
Quests in low level zones award such a miniscule amount of XP towards the cap that it's not worth discussing.
Here is a the url for the original forum: http://us.battle.net/wow/en/forum/topic/1965575069#1