If the adventure has multiple level ranges, the GM will need to calculate the group’s Average Party Level (APL) to determine which range to use.

APL = (sum of character levels) / (number of characters)

Divide the total number of character levels by the number of characters in the party, rounding to the nearest whole number. (This is an exception to the usual ‘round down’ rule.) If the result of the Average Party Level calculation ends with 0.5, the players decide whether to round up or down.