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Damage modification is a system of multipliers used to change the damage dealt in a battle. These modifiers affect how the damage is calculated by multiplying the move's base power in various ways. These modifiers range from doubling to halving and even negating the damage done.

Type effectiveness

Since each move has an elemental type, its effectiveness is largely determined by the targeted Pokémon's type. Moves can have regular effectiveness or be super effective, not very effective, or not effective at all. The effectiveness of types against one another has varied among generations, see this page for its Generation I iteration and this page for the current model.

Super effective

"Super effective" redirects here. For the webcomic, see Super Effective (webcomic).

When a move is super effective, it inflicts double the damage it would normally do. For example, a move like Megahorn used against a Template:Type2 Pokémon will be super effective because Template:Type2 moves are super effective against Psychic-types. This effect can stack up; for example, a Pokémon that is Rock/Ground and is hit by a Template:Type2 move like Surf will be damaged four times as much by the move as a Template:Type2 Pokémon would be, because both Rock and Ground Pokémon are weak to Water moves.

Not very effective

When a move is not very effective, or resistant, it deals half of the damage it would normally do. This works exactly like super effective moves, and can stack up. For example, a Steel/Rock Pokémon will be damaged by a quarter of the amount by a Template:Type2 move. Likewise, a Normal/Flying Pokémon hit by a Template:Type2 move will be damaged normally, as Normal's weakness to Fighting is canceled out by Flying's resistance to it.

Not effective

When a move is not effective, it does not damage the Pokémon at all and that Pokémon is "immune" to all attacks of that type; the move will yield a message of "It does not affect the Pokémon", phrased in the present tense (whereas a move that simply missed yields "It did not affect the Pokémon", past tense). Certain elemental types are also immune to specific status moves, such as Template:Type2 Pokémon being immune to the Template:Type2 Thunder Wave, or Template:Type2 Pokémon being immune to Leech Seed.

Critical hit

A move will sometimes inflict a critical hit against another Pokémon. This will double the damage done after type effectiveness calculations occur, or triple it if the Pokémon has the Sniper ability.

Generation I

050Diglett.png This section is incomplete.
Please feel free to edit this section to add missing information and complete it.

Critical hits ignore stat modifiers, even if beneficial to the attacker. In this generation only, the probability of landing a critical hit is based on a Pokémon's base Speed. Specifically, for a normal move such as Tackle, the probability of landing a critical hit is

Base Speed / 512

For example, Clefable, with a base Speed of 60, has roughly a 11.7% chance of landing a critical hit on a normal move. For moves with a high critical hit ratio such as Slash, the probability of landing a critical hit is

Base Speed / 64

For example, Clefable, with a base Speed of 60, has roughly a 93.8% chance of landing a critical hit on a move with a high critical hit ratio.

If the result of the second formula equals or exceeds 100% (for Pokémon with a base Speed of 64 or higher), then the result is rounded down to 255/256 or about 99.6%.

Focus Energy and Dire Hit were intended to quadruple the critical hit rate, but due to a glitch, they instead quarter the critical hit rate. This was fixed in Pokémon Stadium.

Generation II onwards

Starting in Generation II, the chance of a critical hit is no longer based on the Pokémon's speed, but rather the chance is the same for each Pokémon. Similar to stats, there are temporary in-battle stages used to calculate the probability a particular move will be a critical hit. The stages are as follows:

Stage Percentage of critical hit
1 6.25%
2 12.5%
3 25%
4 33.3%
5 50%

An attacking move will always start out in stage 1. There are several ways to increase a move's stage (and therefore, chance that it will be a critical hit), as detailed in the table below.

+2 +2 +1 +1 Using a move with a high critical-hit ratio
+1 +1 +1 +1 Holding a Scope Lens
+1 +1 Holding a Razor Claw
+2 +2 +2 +2 Holding a Stick (if the Pokémon is Farfetch'd)
+2 +2 +2 +2 Holding a Lucky Punch (if the Pokémon is Chansey)
+1 +1 Having Super Luck as its ability
+1 +1 +2 +2 Being under the effect of Focus Energy
+1 +1 +1 Consuming a Lansat Berry (or being passed its effect)
+1 +1 +1 +1 Using Dire Hit on it
+2 Using Dire Hit 2 on it (Wonder Launcher only)
+3 Using Dire Hit 3 on it (Wonder Launcher only)

Even if enough additions are obtained, there is no way for a move to be in a stage higher than 5; if the sum is greater, it will still only have a 50% chance of landing in a critical hit. The effects of Focus Energy, the Lansat Berry, and the several versions of Dire Hit cannot stack with themselves or each other. Additionally, if the move used is Storm Throw or Frost Breath, it will always result in a critical hit. On the other hand, if the target Pokémon has the ability Battle Armor or Shell Armor, or is under the effect of Lucky Chant, a move will never be a critical hit, no matter the stage.

When a move scores a critical hit, damage is calculated based on either the modified or unmodified attack and defense stats, whichever is more advantageous to the attacker. For example, an attacker who has used Swords Dance and then makes a critical hit will get the benefit of the increased Attack, while one affected by Charm will use its normal Attack score. Another example would be if a team had Light Screen or Reflect on it and the attacker scored a critical on the team with the certain wall; the defense added by the wall would then be ignored, and the attacker would do double damage. However, it does not ignore modifiers caused by items or abilities such as Eviolite, Defeatist, or Slow Start.

Same-type attack bonus

Main article: Same-type attack bonus

A move used by a Pokémon that is of the same type as the move itself will do 150% of its normal damage, such as a Template:Type2 move used by a Fire-type Pokémon. Dual-typed Pokémon will receive this bonus for both of their types, and a Pokémon whose type can change in-battle will receive the bonus for whatever type they are when they make the move. Pokemon with Adaptability have this increased to 200% (an effective boost of ~33.3%).


Main article: Weather conditions

Template:Type2 and Template:Type2 moves' damage will be modified by rain and sunshine. If Rain Dance causes a downpour, Water-type moves will do 50% more damage and Fire-type moves will do 50% less damage. If Sunny Day causes harsh sunlight, Fire-type moves will do 50% more damage and Water-type moves will do 50% less damage.


Main article: Ability

Abilities come in a wide variety, and have various effects on damage modification. These affects range from increasing and decreasing the power of moves of a specific type, granting immunities, and even changing the power of moves affected by other damage modifiers. These abilities include:


See also: Type-enhancing item

Some held items increase the power of an attack by a small percentage. Most of these items boost attacks only of a certain type by 20%. Some items can also modify damage by boosting the attacker's offensive stats or the victim's defensive stats. Some berries also weaken an opponent's super effective move.

Other held items that modify damage include:


A number of other variables can affect the amount of damage caused by an attack.

  • If the attacker is burned and their ability is not Guts, their physical damage will be decreased by half.
  • In a double battle, moves that hit multiple targets do 75% of the damage they do in one-on-one battles.
  • Reflect and Light Screen decrease opponents' physical and special attacks, respectively, by 50% in a one-on-one battle and 33% in a double battle.

Randomization adjustment

Every time a regular attack is executed, the actual damage caused is adjusted by a random multiplier - an integer percentage between 85% and 100%.

In Generations I and II, the random modifier does not have uniform probability for all percentages between 85 and 100. This is because the computer will generate a random number from 217 to 255 (217 is about 85.09% of 255), multiply it by 100, and then divide it by 255, to get the random number from 85 to 100 that the computer will divide by 100 to get the final adjustment.

As a result, the odd numbers from 85 to 89 and the even numbers from 90 to 98 have a 7.69% (3 in 39) probability of being chosen, while the even numbers from 86 to 88 and the odd numbers from 91 to 99 have a 5.13% (2 in 39) probability of being chosen. The number 100, the least probable number, has a mere 2.56% (1 in 39) chance of being chosen.

In all subsequent games, the random adjustment is determined by generating a 4 bit number (0 through 15). The computer then subtracts it from 100, and then divides the result by 100 to get the final adjustment. This results in the same integer percentage between 85% and 100%, with an even distribution of occurence.

Damage formula

The damage dealt when a Pokémon uses a damaging move depends on its Attack or Special Attack stat, the opponent's corresponding Defense or Special Defense stat, and the move's base damage. In addition, the various circumstances explained above will also affect the damage dealt.

The damage formula is the following:


  • Level is the level of the attacking Pokémon.
  • Attack and Defense are the working Attack and Defense stats of the attacking and defending Pokémon, respectively. If the attack is Special, the Special Attack and Special Defense stats are used instead. Some moves, eg. Psystrike use other stat than usually move of this category would use (in case of Psystrike, it uses Special Attack and Defense).
  • Base is the base damage of the attack.
  • Modifier is calculated as follows:


  • STAB is the same-type attack bonus. This is equal to 1.5 if the attack is of the same type as the user, and 1 if otherwise.
  • Type is the type effectiveness. This can be either 0, 0.25, 0.5, 1, 2, or 4 depending on the type of attack and the type of the defending Pokémon.
  • Critical is 2 for a critical hit, 1 otherwise. For Pokémon with Sniper, it is 3 for a critical hit.
  • other counts for things like held items, field advantages, and whether the battle is a double battle or not.
  • rand is a random number from 0.85 to 1.00 with an even distribution.

The result is rounded down unless it is less than 1, in which case it's rounded up to 1. All damaging moves always do at least 1 damage if they hit.


Imagine a level 75 Glaceon that has the following stats:

HP: 201
Attack: 123
Defense: 181

It uses the move Ice Fang (Ice, physical, base damage 65) against a level 78 Garchomp:

HP: 270
Attack: 210
Defense: 163

Garchomp is Dragon/Ground, so it has a double weakness to Ice. Thus, Type = 4. Additionally, Glaceon, being an Ice-type, receives STAB, so STAB = 1.5.


We then plug Modifier into the rest of the formula:



So depending on luck, Glaceon will do damage in the range 170-200 HP. Despite Garchomp's double weakness to Ice, Glaceon's Ice Fang will not defeat it in a single hit.

Garchomp is up next. Garchomp gets a critical hit (Critical = 2) on Earthquake, a physical Ground move with 100 base damage. With its Ice type, Glaceon is neither weak nor resistant to Garchomp's attack, so Type = 1. Garchomp is Dragon/Ground, so it receives STAB, making STAB = 1.5. Say that Garchomp is also holding an Earth Plate, which powers up Ground-type moves by 20%. Then Other = 1.2.


We insert the stats and Modifier in the formula and get:



We see that Garchomp's attack will do anywhere from 241 to 284 damage, which is more than enough to take the Glaceon out in one hit.