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Calcimator

Random Encounter Calculator

Calculate expected encounter frequency from travel duration, check frequency, and danger level.

Inputs

%
%

Results

Expected Encounters

2.8

Prob. of At Least One94.8%
Day Encounters2.3
Night Encounters0.5
Total Checks20
Effective Day %15%
Time Lost to Encounters1.4 hours
Total Travel Hours41.38
How to Use This Calculator
  1. Set the terrain type (dungeon, wilderness, urban, sea) and the party level.
  2. Enter the encounter frequency: rolls per in-game hour or day.
  3. Set the encounter chance as a percentage or dice threshold.
  4. Review the Encounter Probability Per Day and the Expected Number of Encounters.
  5. Use the Encounter Type Distribution to pre-generate a table of appropriate encounters.

How the result changes with Travel Days

Travel DaysExpected Encounters
9.95.4
3217.6
5932.5
8144.6

What each input means

Travel Days
Number of days of overland travel.
Day Checks
Random encounter checks per day (typically 2-4).
Day Encounter Chance
Base percentage chance per check (before danger modifier).
Night Encounter Chance
Chance of encounter during long rest.
Danger Level
Multiplier applied to base encounter chance.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Travel Days = 5, Day Checks = 3, Day Encounter Chance = 15, Night Encounter Chance = 10 = 5 input(s) provided
  2. Calculate Expected Encounters
    Expected Encounters
    2.8 = 2.8
  3. Calculate Prob. of At Least One
    Prob. of At Least One
    94.8 = 94.8
  4. Calculate Day Encounters
    Day Encounters
    2.3 = 2.3

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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