If you’re starting out as a player or DM in Dungeons & Dragons, you’ve probably seen a lot of references to “DC” or “Difficulty Class.” DC is one of the core ideas in D&D’s mechanics and it’s essential to understand how it works.
What Is the Difficulty Class in DnD 5e?
DC represents the difficulty of any given skill check. It is a number you have to match or beat for your skill check to succeed. These skill checks can be active checks that require rolls, but DC also applies to passive skill checks.
How Difficult Is It To Succeed on a Roll of a Certain DC?
The Player’s Handbook (page 174) and The Dungeon Master’s Guide (page 238) give some examples to demonstrate the difficulty of different rolls.
It’s also quite easy to figure out the likelihood of succeeding on a given roll.
For example, a character with a +10 bonus to a skill needs to roll a 20 to succeed on a DC30 “Nearly Impossible” skill check.
Even a highly proficient character only has a 1 in 20 (or 5%) chance to succeed such a difficult roll.
Meanwhile, an unskilled commoner with a +0 modifier to a roll only needs to score 10 or higher to succeed on a DC10 “Easy” roll.
Including a roll of 10, there are 11 possible results on a d20 dice that will result in a success, so the chance of succeeding is 11 in 20, or 55%.
How To Choose the Difficulty Class for a Roll
DC is a versatile tool that gives DMs a lot of power to improvise – there aren’t concrete rules for which tasks should fall into which difficulty class.
That said, some example DCs might help you in determining the DC of various tasks in your game.
Very Easy tasks should be things that most people can expect to succeed at most of the time.
That said, an unskilled commoner (i.e. someone with a +0 modifier) will still fail these tasks roughly 20% of the time, so completely trivial tasks, like tying your shoelaces, don’t belong here.
Examples of Very Easy tasks include:
- Climbing over a low fence.
- Finding firewood in a forest when the weather is dry.
Easy tasks are the next difficulty tier up. An unskilled commoner will succeed in these tasks over half of the time. These might include:
- Finding a piece of well-documented information in a library.
- Leaping across a narrow stream.
Moderately difficult tasks are where we start to reach tasks that require some degree of skill or training. These could include:
- Calming a panicked horse.
- Performing a pleasing song to a small crowd in a tavern.
Hard tasks are tasks that an untrained person isn’t capable of unless they get very lucky. Examples of Hard tasks are:
- Finding firewood in a rainstorm.
- Tracking a wild animal.
Very Hard tasks are a challenge, even for trained adventurers. Some examples of Very Hard tasks are:
- Learning long-forgotten historical facts in a library by inferring information from multiple sources.
- Convincing one of the BBEG’s henchmen to release you from a cell.
- Maintaining your balance on top of a swiftly moving carriage.
Nearly Impossible tasks are incredible feats that, while technically possible, pose a very high risk of failure for even the most specialized adventurers.
- Surviving a fall from a great height.
- Crossing a desert alone on foot.
Difficulty Class and Critical Successes and Failures
Counter to what you might have heard, D&D 5E has no rules for critical success or failure on ability rolls!
Rolling a “natural 20” or “natural 1,” meaning a 20 or 1 prior to adding modifiers, results in a critical failure or success when making attack rolls. This rule is often, intentionally or accidentally, modified to include ability rolls.
There are problems with applying this rule to ability rolls.
A 5% chance of success is low but significant, and this rule means that every attempt that anyone makes at any task will have, at minimum, a 5% chance to succeed.
That means someone with no musical training has a 5% chance to successfully perform the most beautiful song that was ever played.
A person who can’t read has a 5% chance to successfully write a world-changing novel. Your bard has a 5% chance to successfully seduce the dragon!
This can be a fun rule for more lighthearted campaigns, but it can lead to some very silly results. Unless you’re intending to run a slightly wackier campaign, I’d suggest avoiding this rule.
DCs for Trivial and Impossible Tasks
There are some tasks that shouldn’t have DCs!
Some tasks are too trivial to warrant a roll. For your average untrained person, basic, everyday tasks like getting out of bed, getting dressed, walking to work, etc. should have a negligible chance of failure.
The DC for these tasks should be so low that it’s impossible to fail.
If this is the case, it’s a waste of time to force players to repeatedly roll for these tasks. You shouldn’t make players roll dice unless there’s at least some possibility of failure.
Conversely, some tasks are completely impossible. It’s impossible to survive falling into an active volcano, regardless of how much training you have or how high your roll is.
It’s impossible to convince the king to hand over control of his kingdom to you, regardless of how silver-tongued you are.
The DC for these tasks is so high that no character could ever have high enough modifiers that they become possible. You shouldn’t make players roll dice unless there’s a possibility that they’ll succeed.