Critical hit
 This article is about the random event. For the video podcast, see It's Super Effective (podcast) → Related podcasts.
A critical hit (Japanese: 急所 pressure point) is a (generally) random event that multiplies the damage of a damagedealing move. When one occurs, the game will display the message "A critical hit!" (Japanese: 急所に 当たった！ Hit a pressure point!) after the damage is dealt.
Contents
In Generation I
Damage
When a move lands a critical hit, the attacker's level will be doubled during damage calculation, which approximately (but not quite) doubles the damage dealt. A rough formula for the damage multiplier is (2L+5)/(L+5)
where L is the attacker's level; as a result, lowerleveled Pokémon have a smaller critical hit boost than higherleveled Pokémon. For example, a level 5 Pokémon will inflict about 1.5× damage on a critical hit, while a level 20 Pokémon will inflict 1.8× and a level 95 Pokémon will inflict 1.95×.
Critical hits ignore all stat stage modifiers and the halved Attack from burn. This includes beneficial stat modifiers as well, making it possible for a critical hit to deal less damage than a noncritical hit if the attacker has at least doubled their Attack/Special or the target's Defense/Special is at least halved.
Probability
Whether a move scores a critical hit is determined by comparing a 1byte random number (0 to 255) against a 1byte threshold value (also 0 to 255); if the random number is less than the threshold, the Pokémon scores a critical hit. If the threshold value is T, then this means the probability (P) of scoring a critical hit is P = T / 256
. (Note that this means it is impossible for a critical hit to be guaranteed; there will always be a 1/256 chance that a critical hit will not be scored.)
The value of T is based on a Pokémon's base Speed. For a normal move, T is half the base Speed:
T = BaseSpeed / 2
orP = BaseSpeed / 512
Due to a bug, Focus Energy and Dire Hit lower a Pokémon's chance of scoring a critical hit instead of raising it, dividing T by 4:
T_{FE} = BaseSpeed / 8
orP_{FE} = BaseSpeed / 2048
If the move being used has a high criticalhit ratio (Crabhammer, Karate Chop, Razor Leaf, or Slash), T is multiplied by 8:
T_{HighCHR} = BaseSpeed * 4
orP_{HighCHR} = BaseSpeed / 64
Both effects may also be active at the same time. This would result in:
T_{FE+HighCHR} = BaseSpeed
orP_{FE+HighCHR} = BaseSpeed / 256
At all times, the maximum value for T is 255 (which equally means the maximum value for P is 255/256). All operations that factor into T are also integer operations (meaning divisions are rounded down to the nearest whole number). (Note that the division in P = T / 256
is not rounded.) Due to the process the game uses to compute T, BaseSpeed is also effectively rounded down to the nearest even number.
In Pokémon Stadium
In Pokémon Stadium, the threshold value T is determined by a different formula.
For a normal move, T is:
T = ( BaseSpeed + 76 ) / 4
orP = ( BaseSpeed + 76 ) / 1024
Focus Energy is slightly more complicated than in the core games, but it does correctly raise the chance of a critical hit instead of lowering it:
T_{FE} = ( BaseSpeed + 236 ) / 2
orP_{FE} = ( BaseSpeed + 236 ) / 512
If the move being used has a high criticalhit ratio (Crabhammer, Karate Chop, Razor Leaf, or Slash), T is multiplied by 8:
T_{HighCHR} = ( BaseSpeed + 76 ) * 2
orP_{HighCHR} = ( BaseSpeed + 76 ) / 128
If both effects are active at the same time, then:
T_{FE+HighCHR} = ( BaseSpeed + 236 ) * 4
orP_{FE+HighCHR} = ( BaseSpeed + 236 ) / 64
Since 236 * 4 is well beyond 255, any Pokémon will have a maximum chance to score a critical hit if both effects are active.
As with the core games, the maximum value for T is always 255 (or 255/256 for P) and any divisions that factor into T are rounded down to the nearest whole number. Due to the process the game uses to compute T, BaseSpeed is also effectively rounded down to the nearest multiple of 4.
Generation II onwards
Damage
In Generations IIV, a critical hit deals 2 times the damage a move would otherwise do. From Generation VI onwards, a critical hit deals 1.5 times a move's normal damage.
In Generation II, when a move scores a critical hit, all stat stage modifiers, the halved Attack from burn, and the defensive boosts from Light Screen and Reflect are ignored if the target's defending stat stage (Defense or Special Defense) is greater than or equal to the attacker's attacking stat stage (Attack or Special Attack). From Generation III onwards, when a move scores a critical hit, the attacker's negative stat stages, the defender's positive stat stages, and the defensive boosts from Light Screen, Reflect, and Aurora Veil are always ignored. However, the halved Attack from burn is no longer ignored.
 Examples
 If the attacker is using a physical move and is at +2 Attack stages while the target is at +1 Defense stage...
 Gen II: a critical hit will not ignore either stat. (Damage with a critical hit will have an 8/3× modifier.)
 Gen IIIV: a critical hit will ignore the Defense boost. (Damage with a critical hit will have a 4× modifier.)
 Gen VI+: a critical hit will ignore the Defense boost. (Damage with a critical hit will have a 3× modifier.)
 If the attacker is using a physical move and is at 1 Attack stages while the target is at 2 Defense stage...
 Gen II: a critical hit will not ignore either stat. (Damage with a critical hit will have a 2.64× modifier.)
 Gen IIIV: a critical hit will ignore the Attack drop. (Damage with a critical hit will have a 4× modifier.)
 Gen VI+: a critical hit will ignore the Attack drop. (Damage with a critical hit will have a 3× modifier.)
Other factors
The Abilities Battle Armor and Shell Armor and the effect of Lucky Chant will prevent any critical hit being scored on a Pokémon.
The moves Storm Throw and Frost Breath will always result in a critical hit (unless prevented by one of the above effects). The move Laser Focus guarantees the next move to score a critical hit.
If a Pokémon with the Sniper Ability gets a critical hit, the damage dealt will be multiplied by an additional factor of 1.5.
Pokémon with the Ability Merciless will always score critical hits on poisoned Pokémon (unless prevented by one of the above effects).
Probability
The probability of landing a critical hit is no longer based on the attacker's base Speed, but rather is based on a fixed formula for all Pokémon. Similar to stats, there are temporary inbattle stages used to determine the probability that a particular move will be a critical hit.
Stage  Chance of critical hit  

Gen IIV  Gen VI  Gen VII onwards  
+0  1/16 (6.25%)  1/16 (6.25%)  1/24 (~4.167%) 
+1  1/8 (12.5%)  1/8 (12.5%)  1/8 (12.5%) 
+2  1/4 (25%)  1/2 (50%)  1/2 (50%) 
+3  1/3 (~33.3%)  Always (100%)  Always (100%) 
+4 and above  1/2 (50%) 
If a Pokémon has maximum affection, the probability from above is multiplied by 2.^{[1]}
An attacking move will start out at stage 0, but there are several ways to increase a move's stage as detailed in the table below. An effect cannot stack with another effect in the same column, including itself.
Change  Attack property  Held item  Ability  Triggered 

+1 stage  Moves with a high criticalhit ratio (Gen II: +2 stages) 
Razor Claw Scope Lens 
Super Luck  — 
+2 stages  10,000,000 Volt Thunderbolt  Stick (for Farfetch'd only) Lucky Punch (for Chansey only) 
—  Focus Energy / Dire Hit (Gen II: +1 stage) Lansat Berry ZForesight, ZSleep Talk, ZTailwind, ZAcupressure, ZHeart Swap Dire Hit 2 (Wonder Launcher only) 
+3 or more stages 
—  —  —  Dire Hit 3 (Wonder Launcher only) 
Note that it is possible for a Pokémon to acquire the effect of a Lansat Berry even if it is already holding another item, through the use of Baton Pass, Pluck, Bug Bite, or Fling; or by obtaining another item after consuming the Berry, such as via Thief or Symbiosis.
In other languages

See also
References
This game mechanic article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games. 