The term attacks per round (APR) refers to how many attacks a creature is able to make during a round (6 seconds). The base attacks per round is determined by the creature's base attack bonus (BAB) — or unarmed base attack bonus (UBAB) in the case of a monk fighting unarmed or with a kama. Even though BAB continue to increase at epic levels, a character's maximum number of attacks is determined by his or her BAB at character level 20.
|BAB||Attack bonuses||Attacks per round||Unarmed progression (monk)||Unarmed APR (monk)|
Additional attacks may be gained by using an off-hand weapon or with other effects or feats. For example, haste provides an extra attack per round, and improved two-weapon fighting provides an extra off-hand attack.
Attacks per round are also split up among three flurries.
Attacks per round are split into three sequences, each starting at full base attack and decreasing by -5 or -3 with each successive attack. Main attacks are described above; they suffer from dual-wielding penalties and can benefit from a monk's unarmed attack progression (the -3). Free attacks are generated by feats, magical effects, and attacks of opportunity; they ignore dual-wielding penalties and never benefit from a monk's unarmed attack progression. Off-hand attacks are generated by wielding two weapons simultaneously; they suffer from dual-wielding penalties and never benefit from a monk's unarmed attack progression.
A character's attack progression proceeds as main attacks, followed by free attacks (made with the main hand), followed by off-hand attacks. An exception to this progression is made when free attacks are generated by activity (such as an attack of opportunity or a cleave attack). If a free attack is generated while the off-hand sequence is active, that free attack is converted to an off-hand attack and added to that sequence. If a free attack is generated while the main sequence is active, a fourth sequence of attacks is partially created. This fourth sequence suffers from dual-wielding penalties and can benefit from a monk's unarmed attack progression. It is only partially created, though, in that attacks in this sequence still occupy a spot in the main progression. Essentially, a regular attack is "promoted" and given the base attack of the fourth progression, but the following regular attack will be at -10 (or -6) relative to the attack prior to the promoted one. The number of attacks in the round is kept at the expected value by adding a free attack, to be taken when that sequence becomes active.
For example, suppose a level 20 character with a monk level, great cleave, and improved two-weapon fighting has a BAB of 9 and is under the influence of divine power, haste, and flurry of blows. If this character wears no armor and wields two kamas that produce an attack bonus of 29 for each hand (before applying dual-wield and flurry penalties), then the following attack progression could be produced.
Main: +25 +22 +19 (regular);
Free: +27 +22 (divine power), +17 (haste), +12 (flurry of blows), +7 +2 (great cleaves);
Off-hand: +25 (regular), +20 (great cleave), +15 (improved two-weapon fighting).