Free D&D / TTRPG combat pacing predictor. Enter players, character level, monster count, and player decision speed; outputs estimated rounds, real-world minutes, and a schedule warning ("don't start near end of session").
Built and maintained by Paul Clark, Redmoon Software
Use before designing the climactic fight of a session — knowing the duration helps you pace narrative beats around it.
Encounter difficulty calculators (Kobold+) tell you "is it deadly?" but not "is it long?". This is the time-budget companion.
⚠ Don't start this near the end of your session.
Per-turn time = 60 s + level × 10 s, multiplied by the decision-speed selector.
Round estimate is bounded between 2 and 8: more monsters extend the fight, higher level shortens it (better burst damage).
Total = (players + monsters) × rounds × per-turn. Most 5e fights land between 30 and 60 minutes.
Tuned for D&D 5e-style combat but useful for any d20 system. Adjust the decision-speed selector for faster systems (Blades in the Dark, PbtA).
No — only duration. Combine with your system's encounter-budget calculator for difficulty.
Most table time is spent deciding actions rather than rolling dice, so slow or indecisive players can double the real-world minutes for the same number of rounds. Groups that plan turns in advance finish combats far faster.
Each extra monster adds its own turn, initiative slot, and set of attacks to resolve every round, so total time grows with both monster count and round count. A handful of weak enemies can take longer to run than one tough boss.
Input
4 players, level 3, 4 monsters, average decision speed.
Output
4 rounds, ~70 s/turn, ~37 min total.
8 combatants × 4 rounds × 70 sec = 2,240 s ≈ 37 min. Add narration overhead for a real ~45-min fight.
Encounter-building maths in most systems allocates a budget across a day of adventuring rather than sizing a single fight. That is the part most often missed: a party's resources are designed to deplete across several encounters, and a single "balanced" fight against a fully rested party is usually easy because nothing has been spent.
The defaults here — four players at level 3 against four monsters — are the shape most encounter tables are calibrated against.
The strongest predictor of difficulty is not the total challenge value but the number of turns each side gets. Four monsters at a quarter of the strength each are considerably more dangerous than one at full strength, because they act four times to the single monster's once and can focus their attacks.
A single large enemy against a full party is the classic mismatch in the other direction: it is outnumbered on actions and frequently loses despite an alarming statistics block. Any budget arithmetic that ignores this will misprice both cases, so treat the number as a starting point and adjust for how many turns each side actually gets.
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