Health

Health (commonly known as HP, an abbreviation for Health/Hit Points) is the amount of life a unit or structure has. Max health is the cap on life any unit can have. Current health is directly reduced by damage and is regained in many different ways.

Every unit and structure has their max and current health displayed as a bar above their models. When displayed over a champion's model in game, the health meter is displayed as segmented bars.

Additionally, for your own champion, it is represented in the interface as a green bar with two numbers ( # / # ): the first one represents the actual life available at the moment, while the second is the maximum amount of health the champion can have. If a champion's health reaches zero and he doesn't have any abilities preventing it, death will occur. Max health scales additively with every bonus health point and increases with each level, meaning that each bonus point acquired directly affects the statistic.

At level 18 base health ranges from 1600 health to  2381 health. See here for the complete list.

Effective Health
Effective health is considered as the amount of health that a champion has plus 1% per unit of defense as extra health due to damage reduction. In other words, effective health is the amount of damage the enemy needs to kill the champion.

For example, a champion with 1000 HP and 0 armor and an enemy with auto-attacks that deals 100 damage, then the champion can be killed when 10 auto-attacks. If the champion has 100 armor, the champion prevents 50% of the damage so the enemy deals 50 damage with each auto-attack. Therefore, as each auto-attack deals half damage and the enemy needs to execute double the amount of auto-attacks to deal 1000 damage. So the enemy instead of dealing 1000 damage before reduction to kill the target, the champion has to deal 2000 damage before reduction to kill the target.

There is effective health for physical damage and for magical damage.

In short the formula is:


 * Physical Effective Health = Max Health(1(Armor / 100))


 * Magical Effective Health = Max Health(1(Magic Resist / 100))

Health as a casting resource
A few champions also use their own health to cast abilities instead of mana:

Other champions' abilities

 * costs health per use
 * costs health per attack

Personal Health as scaling
These use the champion's personal health pool to increase the magnitude of the ability. It could involve total or extra health. By building health items you can receive more benefit and power from these abilities in most situations.
 * receives bonus health regeneration per second equal to 0.3% of his maximum health.
 * gains attack damage for every 1% of health he is missing.
 * heals of his maximum health over 12 seconds.
 * regenerates 0.5% of his maximum health per second if he hasn't been damaged by a Monster (excluding minions), Champion or Tower for 9 seconds.
 * heals 2% of his maximum health over 4 seconds every time he uses an ability.
 * grants him a shield equal to 10% of his maximum health which recharges if he hasn't been damaged for 10 second.
 * heals 7% of his maximum health when he attacks with 5 magical sap stacks.
 * grants him a shield that blocks for a flat amount plus 10% of his bonus health.
 * increases his attack damage by 1% of his maximum health.
 * deals of her maximum health in additional magic damage per second.
 * does 10% of his bonus health in additional magic damage.
 * heals allied champions that damage a life-tapped enemy by a flat amount plus 1.5% of his maximum health over 3 seconds.
 * passively gains attack damage for every 1% of health he is missing.
 * increases his ability power by 1 for every 40 bonus health points.
 * does 15% of his bonus health in additional magic damage.
 * gives her a shield equal to 10% of her maximum health when she hits an enemy with one of her activated abilities.
 * heals 30% of his maximum health over 6 seconds if he gets under 30% health.
 * does 15% of his bonus health in additional physical damage.

Damage scaling from enemy health
These abilities grant extra damage based on the target's maximum, current or missing health. Typically, the more health the target has (or has missing), the more damage these abilities will deal. Because of this they are more powerful against high-health targets, but their effect against low-health targets should not be ignored. Also note this type of extra damage is always capped against minions and monsters to prevent players dealing massive damage to high health pool monsters like Baron.
 * harms nearby enemies for a flat magical damage plus  of their maximum health per second.
 * causes his spells to add a debuff to the target dealing 2% of their maximum health each second as magic damage for 4 seconds.
 * deals either a flat amount of magic damage or of the target's current health as magic damage (whichever is higher).
 * Deals magic damage equal to a base amount plus  of the target's current health.
 * Deals magic damage equal to a base amount plus  of the target's missing health.
 * impales all enemy champions in the targeted area, dealing  of their current health as magic damage
 * deals a flat amount plus of target's missing health in magic damage over 3 seconds.
 * deals a flat amount plus of target's missing health in magic damage.
 * gives his first attack on a target bonus physical damage equal to of the target's current health.
 * does of the target's maximum health as bonus magic damage.
 * allows him to deal bonus physical damage equal to 12% of the targets missing health to Isloated enemies.
 * gives him a temporary buff to his autoattacks dealing  of the target's maximum health as bonus magic damage.
 * deals flat physical damage plus 8% of the target's missing health.
 * harms enemies within an area for  of their maximum health per second.
 * deals  of the target's maximum health in magic damage to the target, dealing half the damage initially and the other half over 10 seconds.
 * empowers him for 15 seconds, dealing magic damage equal to  of nearby enemies maximum health per second for the duration.
 * deals a flat amount plus 8% of her target's maximum health as magic damage.
 * adds marks after each spell or auto attack on her target. After 3 of these marks, the affected target takes a flat amount plus of the target's maximum health as true damage.
 * adds marks through auto attacks which can be detonated via any of his other spells for magic damage equal to  of the affected target's maximum health per mark. Maximum 3 marks for   damage.
 * deals additional physical damage equal to  of the target's maximum health on every 3rd attack on the same target.
 * deals 1% more damage for every 1% of health the enemy is missing.
 * deals flat magic damage or of the enemy's maximum health (whichever is higher).
 * does 15% of current target health as physical damage to all nearby enemies.

Items

 * increases your attack damage by 1.5% of your maximum health.
 * dealing spell damage burns for an additional 3.5% of the target champion's maximum health in magic damage over 2 seconds. Each second burned consumes a charge. Up to 18 charges are generated when not in use.
 * deals 5% of the target's current health in physical damage (90 max vs. minions and monsters) every autoattack.
 * heals a target for 15015% of their missing health. (180 second cooldown)
 * deals 15% of the target's max health in magic damage upon activation.
 * dealing spell damage burns for an additional 6% of the target's current health in magic damage over 3 seconds. If their movement is impaired, they take double damage from this effect. 300 max damage vs monsters.
 * deals 2.5% of the target's maximum health in magic damage every autoattack.
 * gives 1 attack damage for every 2.5% health missing.
 * restores 0.2% of your maximum health every second.

Ways to restore health
A champion's health can be restored in several ways:
 * Health regeneration
 * Using a or.
 * Returning to the spawning pool, which restores a percentage of your maximum health per second.
 * Some max health is granted upon leveling up and with that you regain some current health. Actual health regained is lower depending on how wounded the champion is upon leveling up.
 * Slaying a monster that has Healing Sigil (, and ), will restore health equal to a percentage of their missing health.
 * With life steal or spell vamp, dealing damage to enemies with autoattacks or abilities respectively will restore some health.
 * In addition to life steal, will also restore 5 health on hitting an enemy
 * The passive effect of and  restores 250 health over 8 seconds when leveling up.
 * Using a healing ability or spell, such as or, or.

Champion abilities
Note: Only the addtional health effect of these abilities is shown here, to read more information on each of these abilities, follow the link on each of them.
 * increases his maximum health by when it kills a unit. This buff stacks up to 6 times. Cho'Gath loses half his current stacks (rounded up) upon death.
 * increases the maximum health of the targeted ally by  for 7 seconds.
 * increases his maximum health by for 15 seconds.
 * increases his maximum health by for 15 seconds.
 * increases his maximum health by.
 * permanently increases his maximum health by whenever he kills a unit if  is toggled on.
 * increases his maximum health by 220.
 * increases his maximum health by.

Masteries

 * increases your champion's health by per level (  bonus health at level 18).
 * increases your champion's health by 30.
 * increases your champion's maximum health by.
 * grants the champion +5 health per level if they have.

Runes

 * , and  runes increase maximum health.

Trivia
Aside from, who may obtain any amount of health due to the passive effect of his , the most health any champion can obtain is 12812, being a level 18 with:
 * 6 stacks of level 3
 * A full health runepage
 * 9 Scaling Marks of Health
 * 9 Scaling Glyphs of Health
 * 9 Percent Seals of Health
 * 3 Percent Quintessences of Health
 * All health masteries
 * 6
 * casted by a with the maximum amount of ability power.
 * The health bonus granted from
 * When Cho'gath is revived (As this is the only way to activate its health bonus), Cho'Gath can only use his Feast three times before the Revive bonus wears out. Another champion with Soul Shroud will allow Feast to be used three times. To do this, he must use Feast right when he respawns, another about 54 seconds later and the third one at about 1:48.
 * Alternately, without the aid of an ally, an Elixir of Brilliance may be purchased prior to death, followed by reviving, running to the blue golem camp, and feasting on a small lizard. After obtaining the blue buff, the cooldown provided by the elixir and the blue buff is enough so that after feasting a second time, the third feast is available before the two minutes expires on Revive's health bonus.
 * casted by a with the maximum amount of ability power.
 * The health bonus granted from
 * When Cho'gath is revived (As this is the only way to activate its health bonus), Cho'Gath can only use his Feast three times before the Revive bonus wears out. Another champion with Soul Shroud will allow Feast to be used three times. To do this, he must use Feast right when he respawns, another about 54 seconds later and the third one at about 1:48.
 * Alternately, without the aid of an ally, an Elixir of Brilliance may be purchased prior to death, followed by reviving, running to the blue golem camp, and feasting on a small lizard. After obtaining the blue buff, the cooldown provided by the elixir and the blue buff is enough so that after feasting a second time, the third feast is available before the two minutes expires on Revive's health bonus.
 * Alternately, without the aid of an ally, an Elixir of Brilliance may be purchased prior to death, followed by reviving, running to the blue golem camp, and feasting on a small lizard. After obtaining the blue buff, the cooldown provided by the elixir and the blue buff is enough so that after feasting a second time, the third feast is available before the two minutes expires on Revive's health bonus.

Spreadsheet with calculations (Updated for V3.03)