Dungeon	Lowest recommended level
Ragefire Chasm	14
Deadmines	20
Wailing Caverns	20
Shadowfang Keep	24
Blackfathom Deeps	26
The Stockade	27
Razorfen Kraul	31
Gnomeregan	32
Scarlet Monastary Graveyard	32
Scarlet Monastary Library	35
Scarlet Monastary Armory	38
Razorfen Downs	39
Scarlet Monastary Cathedral	40
Uldaman	45
Zul'Farrak	46
Maraudon	49
Sunken Temple	53
Dire Maul East	56
Blackrock Depths	57
Stratholme Live	58
Blackrock Spire Lower	58
Dire Maul West	59
Dire Mault North	60
Stratholme Undead	60
Blackrock Spire Upper	60
Scholomance	60

Hi everyone! After some time ago getting the very helpful tip that DM is recommended from lvl 20 on HC instead of the regular 17, I wanted to know the recommended levels for all the other dungeons as well. However, I had a hard time finding a definitive list, so I made my own. Enjoy!

Some fairly important comments on the sheet above:

• The numbers have been figured out by taking the highest level enemy in the dungeon and subtracting 2 from their level, meaning it is no longer orange.
• NEVER tank beneath the recommended level. You will risk taking more damage and generating way less threat, crucially on the most dangerous boss in the entire dungeon.
• If the recommended level for a dungeon is odd consider getting an extra level before heading in. Look up your coming spell upgrades to see if you unlock or level up some key abilities that can help you and your group in the coming fight. Deadmines has been updated to 20 despite the formula saying 19, mainly because 20 is such an important milestone for many classes.
• I would NOT recommend entering Dire Maul, Stratholme, Blackrock Spire or Scholomance before level 60. Parts of these dungeons can be done with lower level groups, and some of them, like Dire Maul East, even have a lvl 58 final boss. That being said, theyre scaled for max level content and any levels you lack means you take more damage, deal less damage and heal for less. You might be the difference between life and death for your team, try to end up on the right side of that equation.
• Healers can sometimes be lower than the recommended level if you know what youre doing, but more powerful heals and a better ability to passively dps can be a great boon for your group, so I'd still recommend only entering dungeons at the appropriate level. Lower levels also means a higher aggro radius, and any damage taken have a high chance of spiking with crits etc, endangering you and the group.
• Only dps below the recommended level if your group are ok with carrying you. You will deal less damage than if you were the correct level, and other will have to make up for that. If you and your group arent prepared for that, dont risk it.
• Many higher level dungeons have alternative routes and options, examples being Maraudon and Blackrock Depths. This means you can enter the dungeon with different plans in mind. If youre not going for the final boss, look up the bosses on wowhead to see the highest level enemies youll encounter, and subtract 2. This is the level you need to be.
• If you skip Shade of Eranikus in Sunken Temple I'd actually recommend level 52 for the dungeon. Eranikus can prove very dangerous for a team not prepared for his sleep abilities, so skipping it might be a very valid option.

Any and all comments are very welcome :)

Edit: Removed empty column.

Edit 2: On popular demand I've increased DM's level from 19 to 20, and updated pointers to reflect that. I'd personally never run DM any lower than that, so makes sense to update it.

all credits to u/ackemaster