The Dungeon Master’s Guide gives a handy table of sample DCs for skill checks. However, what they don’t tell you is the context in which they should be used. This article explores the potential skill bonuses at various levels of play and suggests DCs to use in various circumstances.

First, we need to examine what bonuses the characters have. In a group of adventurers, skill bonuses tend to fall into these categories:

• Unskilled users. Let’s assume they have a 10 in the ability score being used.
• Skilled users with a non-primary ability score (that is, one they don’t increase with ability score increases). Let’s assume they have a 12 in the ability score.
• Skilled users with a primary ability score. Rogues using Sleight of Hand with Dexterity. At some point, their Dexterity score will move up to 20. I assume 16 at level 1, 18 at level 4, and 20 at level 8 for these calculations
• Expert users with a non-primary ability score. (Expert = Expertise, available mainly to rogues and bards).
• Expert users with a primary ability score.

Here’s a table setting out the bonuses you can expect from these characters:

Magic items, spells and a couple of feats (for Perception) can alter those numbers, but they’re accurate in most cases.

The basic DCs given in the DMG are as follows:

When you compare the DCs to the bonuses above, you can easily see that “Nearly Impossible” is indeed impossible for most characters, although true experts can do the nearly impossible 40% of the time – or 64% of the time if they have advantage!

One thing to consider when setting DCs is that the titles of those DC bands tell you what the difficulty is in the world; not for your characters. A Hard check may have only a 5% chance of success if all the party are unskilled or be only moderately challenging for expert characters at higher levels.

So, an Unskilled character will fail at a Easy task almost half the time, meanwhile most skilled characters will succeed at that task most of the time – with their chance of succeeding increasing significantly if they’re higher level or they have expertise.

When I set DCs I first consider this: Who is making the check?

• Is one character acting alone?
• Are a party of characters aiding each other?
• Are all the characters acting separately?

If only one character in the party must make the check, then it will be the most skilled character, and a DC of 15 or higher may be appropriate. If each character makes the check separately and suffers the consequences for failure, then unless the check is very easy, many characters will fail.

Consider if the characters must climb a cliff.

• You could ask each character to make the Strength (Athletics) check separately. There’s very limited scope for characters to aid each other.
• You could have the first player to climb it lower a rope. The rope could
  • allow the other characters to climb it without a check,
  • allow characters to climb it with a Very Easy check, or
  • allow them to climb with advantage.

If each character must check – even with advantage – then a Hard check makes the check impossible for anyone with a Strength of 8! However, if you only need one character to succeed, then a Hard check could be a trivial task for a high-level, expert character.

It’s also worth considering if the characters need to make the check to proceed in the adventure. If they can’t get to the end without navigating the cliff, then you don’t want the characters to fail. Use a lower DC! However, if it’s optional then using a higher DC is a good idea.

Do the players need to succeed at multiple checks? If this is the case, consider reducing the DC by 5 from what it would be otherwise. A 50% chance of succeeding with one check becomes a 75% chance of failing with two checks; multiple checks can be brutal for increasing the chances of failure.

Contrariwise, do the players only get one chance to make the check? This is often the case with Arcana, Nature and Religion checks: Either you know something or you don’t. You can’t keep wracking your brain for an answer. If you only get one shot at something, the check should be easier than it would otherwise, especially if it’s necessary for the adventure to proceed.

So, putting these ideas into a table:

If you’re writing a home adventure, you can look at the skill bonuses of the characters and tailor the adventure to them. If you’re writing a published adventure, and so you’re unaware of the skill bonuses, then most checks should be in the realm of DC 10 to DC 15, with a few challenging tasks at DC 20. I’d use DC 5 to 10 for tasks that everyone needs to take where there are penalties for failure.

There’s one final type of skill check: the check for a non-essential task that rewards a character for specializing in a skill. If there’s a hidden panel with a great treasure, or a shortcut to the boss monster (like the garbage chute in the goblin cave of Lost Mine of Phandelver), then you offer an opportunity for those expert skill-users to be rewarded for their choices.