How hard should a D&D 5e check be? DC guide for new GMs
Every time a player says "I try to climb it", you pick a Difficulty Class (DC). Pick too low and nothing feels risky. Pick too high and the table gets frustrated. This page gives the standard 5e DC ladder and what it means in real chances for a typical new character, so you can set a DC in a few seconds. The ladder comes from the free D&D 5e System Reference Document (SRD 5.1, Creative Commons).
The DC ladder
| Task difficulty | DC | Chance with +0 | Chance with +5 | Example |
|---|---|---|---|---|
| Very easy | 5 | 80% | 100% | Notice a loud, obvious noise |
| Easy | 10 | 55% | 80% | Climb a knotted rope |
| Medium | 15 | 30% | 55% | Pick a simple lock |
| Hard | 20 | 5% | 30% | Swim against a strong current |
| Very hard | 25 | 0% | 5% | Leap across a wide chasm in armour |
| Nearly impossible | 30 | 0% | 0% | Persuade a sworn enemy to betray their lord |
The chances are exact: the d20 must show at least DC minus your bonus, so the chance is (21 minus that number) divided by 20, kept between 0% and 100%. A first-level character with a trained skill usually has +4 to +5, while an untrained one has about +0 to +2.
How to choose in the moment
- Ask who could do it. If most adults could, DC 10 or lower. If it needs training, DC 15. If it is impressive even for a pro, DC 20.
- Decide what failure means before you roll. "You fall and take damage" and "you get there but make noise" are both better than "nothing happens".
- Use advantage instead of a lower DC when the situation helps the player (good plan, good tools). Advantage on a DC 15 check with +0 moves the chance from 30% to 51%. Check any number with the d20 odds calculator.
- Do not hide the DC logic. Tell players "that looks hard" or "that looks easy" so their choices stay informed.
Common mistakes
- Setting every DC at 15 because it feels safe. Vary them so a +5 specialist feels special.
- Calling for rolls with no consequence. If the answer is "yes, they find the door", just say so.
- Asking for a roll after a failure again and again for the same task. Either let them succeed at a cost or change the situation.
Preparing a first session? Print the first-session prep sheet, and if you are choosing gear, read the beginner gear guide, which says what to skip.
Source: free D&D 5e System Reference Document 5.1 (Wizards of the Coast, CC-BY-4.0) for the DC ladder; chances computed by us from d20 probability. Examples are our own.