Please note that there is no actual mathematical formula used in battles to determine how much weaker you have gotten over time. You only need to know that as you are hit, you will weaken. This tutorial is to give you a general estimate of how much weaker you can expect to become as the battle goes on.

Battle fatigue plays a huge role in all battles (unless you're an Android, which you only need to worry about the third section) As you take hits and use ki blasts, your power level decreases. Here are some basic methods of calculating the rough loss of power level that you will suffer as battle rages on.

Ki Usage: All energy attacks take a percentage of your ki. When your ki reaches 0%, according to the statistical formula, your power level would be halved. This is not actually true and here is why: Let's say your ki is 1,000, power level is 2,000, and that all of your stats are 250. Over the course of the battle, you have used 50% of your Ki. To calculate the effect losing 50% of your ki would have on your power level, you take 50% of your stamina away (-125). That leaves you with a total stamina of 125. If you re-calculate your stats with 125 stamina instead of 250 (250+250+250+125 = 875) Double that for your power level. Your power level is now 1,750.

You are still drained of 50% ki, however, so you still only have 50% to use in battle. If you were to use 100% of your ki in the example above, your stamina would be 0. Recalculating stats with stamina of zero (250+250+250+0 = 750) Double that for power level, you are now at 1,500.

Taking Damage: Ki usage is not the only way your power level decreases during battle, taking damage also lowers it. This one is trickier because there is no set formula for damage, but it is based on a variety of factors and the given situation during the battle. It also requires a referee to tabulate. Let's assume you have the same stats as in the example above, 250 all stats with 1,000 ki and 2,000 power level. Let's say that the battle referee has determined that after a hard-fought battle, you are at about 50%. This 50% is subtracted from your vitality. That means instead of 250 vitality, you now have 125. If you re-calculate your stats with 125 vitality instead of 250 (250+250+250+125 = 875) Double that for your power level. Your power level is now 1,750.

So then, taking 50% damage and losing 50% ki have basically the same effect but both happening together would be double trouble. You can see, then, how both taking damage and using a lot of ki will wear you down extremely. If you were to use all your ki and take 50% damage, you would be all the way down to 1,250 from 2,000!

Androids: Androids are not affected by either of the above two systems of battle fatigue. Their power level will not lower no matter how much ki they use or how many hits they take. They can, however, be worn down in fights. If an Android's vitality drops below 30%, their gears will begin to slow down and their actions per post in battle are decreased by 1 for the remainder of combat.