3.2 The Limit Bar
The Limit Bar dictates when you can use a certain Limit Break. Depending on your Status Attributes, and which Limit
Level you have chosen to build, it will grow quickly or slowly based
on the damage you take.
A character's Limit Bar is measured in Units. Once a Limit Bar
contains 255 Units, the Limit Bar is full, and the character may use
their Limit Break.
The conversion rate between damage points and Limit Bar Units is as
follows:
Units gained = [[300 * HP Lost / Max HP] * 256 * Status Factor / LNum]
In the above formula, Status Factor is equal to 2.0 while in Fury
Status,
0.5 in Sadness
Status, and 1.0 otherwise.
LNum, on the other hand, is a special number that varies for each
character at each Limit Level. The following table shows the LNum
value for all nine characters at each of their Limit Levels.
Level 1 Level 2 Level 3 Level 4
Cloud 140 324 435 506
Barret 129 240 374 450
Tifa 120 334 509 566
Aeris 200 284 322 436
Red XIII 195 300 389 486
Yuffie 200 300 400 480
Cait Sith 160 180 9590 * 12760 *
Vincent 202 244 319 426
Cid 200 280 380 480
* Cait Sith does not have either a L3 or L4 Limit Break - these numbers
are still in the data, however.
Best Answer
For the best way to get AP for materia, go to the northern crater. Once you get there, go to the bottom (the room just before you fight jenova), but instead of going further down, go to the left and enter. There should be an enemy called "Magic Pot". To beat them, you have to throw them an elixir and then on the next turn hit them. You will receive 1000AP per magic pot you kill.
Every maxed-out materia will get multiplied (even summon materia), with the exception of MASTER materia.