# Hit chance

Hit chance is a calculated statistic that determines whether or not an attack will land. In its simplest form, hit chance is simply a function of accuracy, armour, and affinity; however, various modifiers (such as equipment or Buffs) can change hit chance.

When discussing changes to hit chance, modifiers are either additive (directly affecting hit chance) or multiplicative (affecting one of its variables). Additive bonuses are added directly the final calculation, whereas multiplicative bonuses modify a variable in the calculation. In this sense, accuracy is distinct from hit chance; the latter being a function of the former.

## The hit chance formula

In combat, one's hit chance is the chance of successfully hitting a target (or the chance of a target hitting you), given your accuracy, the armour of your opponent, and the style you are using.

Your hit chance ${\displaystyle H}$ (as a percentage) is calculated as:

${\displaystyle H=\operatorname {Aff} \times \left({\frac {a}{d}}\right)}$

Where:

• ${\displaystyle \operatorname {Aff} }$ is affinity
• ${\displaystyle a}$ is your accuracy
• ${\displaystyle d}$ is the target's armour rating. Generally, this is the sum of their armour and armour bonus granted by their Defence level.

### Affinity

Monster affinity

In player-versus-monster combat, the monster generally has an affinity set for 3 or 4 types of attacks: melee, magic, ranged, and the specific weakness, if it has one. By default, those values are:

• 90 when using the target's specific weakness. (eg. slash, stab, arrows, bolts, air, fire, etc.)
• 65 when using a combat style the target is weak against, but not the specific weakness (eg. melee against a ranger)
• 55 when using a combat style the target is neutral against (eg. melee against a meleer)
• 45 when using a combat style the target is strong against (eg. melee against a mage)

Generic weaknesses to melee, ranged, or magic will use the respective melee, ranged, and magic affinity value rather than the weakness affinity value.

Some NPCs have custom set values for each affinity. For example, some bosses have 40 on all affinity values. Sometimes they may have no set weakness, but the affinities favour (or disfavour) one combat style anyway.

Player affinity

When the target is a player - be that in player-versus-player combat, or when calculating your defending chance in PvM - affinity is calculated a little differently. The neutral affinity is still 55, and up to 10 points are added or subtracted based on the armour the target is wearing for each of the three combat styles - players never have a specific weakness. The player's affinity is shown as Style bonus in the loadout interface; see Affinity#Player affinity and style bonus for details on calculating the actual affinity from style bonus.

## Calculating accuracy

A players total accuracy stat is the sum of their level bonus ${\displaystyle L}$ and weapon tier bonus ${\displaystyle T}$. Both of these values involve the formula ${\displaystyle f(x)={\tfrac {1}{1250}}x^{3}+4x+40}$. If the player has level ${\displaystyle \ell }$ in the relevant attack skill (attack, ranged, or magic), their level bonus is just ${\displaystyle L=f(\ell )}$ (rounded down). For example, a player with 99 attack and no weapon equipped will have (rounded) accuracy ${\displaystyle f(99)=1212}$. Temporary boosts such as overloads and stat-boosting prayers will affect this value. The level-based bonus for a player with level 99 attack/magic/ranged is shown below for various boosts.

Effects Attack/magic/ranged level ${\displaystyle \ell }$ Level accuracy bonus ${\displaystyle L=f(\ell )}$
/ / 109 1512
/ / 111 1578
116 1753
118 1826
120 1902
+ / / 126 2144
+ / / 128 2230
+ / / 130 2317
+ / / 132 2407
+ / / + / / 140 2795
+ / / + / / 142 2898

The accuracy boost from by the player's weapon tier is generally much larger. A weapon of tier ${\displaystyle t}$ accuracy gives an accuracy boost of ${\displaystyle T=2.5f(t)}$. For example, if the player has level 99 ranged and is using a tier 92 bow, then their resulting accuracy is ${\displaystyle A=f(99)+2.5f(92)}$ (rounded down). For example, if a player has 99 ranged and is using a tier 92 bow, they will have an accuracy of 3789 (which is ${\displaystyle f(99)+2.5f(92)}$ rounded down. If a potion temporarily raises their ranged level to 120, they will have temporarily have an accuracy level of 4360 (which is ${\displaystyle f(120)+2.5f(92)}$ rounded down).

Weapon tier ${\displaystyle t}$ Weapon accuracy bonus ${\displaystyle T=2.5f(t)}$
70 1486
75 1694
80 1924
85 2178
90 2458
92 2577
99 3031

### Equipment penalty

Wearing armour of the wrong class, excluding hybrid class, will negatively impact hit chance. Affected item slots include the helm, torso, legs, feet, hands, and off-hand slot. Depending on the weapon type, wearing armour from the class you are strong against (ie. if using Melee, this is Ranged) will result in an accuracy penalty that is 3/2 (x1.5) the item's armour stat. Wearing armour of the class you are weak against (if using Melee, this is Magic) will result in an accuracy penalty that is 4/5 (x0.8) of that item's armour stat. This penalty is designed to reinforce the combat triangle system and to prevent players from abusing the combat triangle weaknesses.

### Accuracy boosts

There are various things that can be used to increase your accuracy rating; these simply multiply your accuracy value by a number, and these can be stacked with one another. These include:

Item Multiplier Percentage
increase
Slot
Dragon battleaxe's special attack, Rampage 0.9 -10%
Extreme dominion medallion 1.01 1%
Scrimshaw of Ranging / Magic / Attack 1.02 2%
Void knight armour 1.03 3%
Defenders / Reprisers / rebounders 1.03 3%
Brawler / Sharpshooter / Runic Accuracy 1.03 3%
Superior Scrimshaw of Ranging / Magic / Attack 1.04 4%
Blood / Shadow / Smoke / Ice Nihil (Familiars) 1.05 5%
Greater Brawler / Sharpshooter / Runic Accuracy 1.05 5%
Master Brawler / Sharpshooter / Runic Accuracy 1.07 7%
Supreme Brawler / Sharpshooter / Runic Accuracy / Berserker / Reckless / Maniacal 1.1 10%
Dragon Slayer Gloves (Dragons only, on Slayer task) 1.1 10%
Focus Sight / Hexcrest / Black mask
Slayer helmet / Full slayer helmet (on Slayer task)
1.125 12.5%
Reinforced slayer helmet (on Slayer task) 1.13 13%
Strong slayer helmet (on Slayer task) 1.135 13.5%
Mighty slayer helmet (on Slayer task) 1.14 14%
Corrupted slayer helmet (on Slayer task) 1.145 14.5%
Salve amulet (Undead only) 1.15 15%
Salve amulet (e) (Undead only) 1.2 20%

### Hit chance boosts

Also known as flat or additive accuracy bonuses. Unlike the above mentioned accuracy bonuses, these add the value directly to your final hit chance, rather than multiplying it. These can also be stacked with one another.

For example, a 10% hit chance bonus adds 10% to 60%, thus becoming 70% hit chance.

Keris (against Kalphites, also 33.3% damage boost and 2.5% chance to deal +200% damage instead +33.3%) 15% Melee
Silverlight, Darklight, and Holy water (against certain demons, also a large damage boost) 20% Melee/Ranged
Keris with Desert amulet 3 or Desert amulet 4 worn (against Kalphites, also 33.3% damage boost and 5% chance to deal +200% damage instead of +33.3%) 25% Melee
Darklight and Holy water (against certain demons; with the Darklight upgrade reward from Dimension of Disaster, also a large damage boost) 30% Melee/Ranged
Balmung (against Dagannoths, also 12.5% ability damage boost (7.5% against Dagannoth Supreme)) 30% Melee
Upgraded Balmung (against Dagannoths, also 22.5% ability damage boost (17.5% against Dagannoth Supreme)) 45% Melee
Dazing Shot and Greater Dazing Shot -10% on your target's next attack Ranged
Hexhunter bow (against magic-classed targets, also 12.5% damage boost) 10% Ranged
Nightmare gauntlets 25% to Snipe, as well as allowing movement Ranged
Fleeting boots and Enhanced fleeting boots 10% to Rapid fire, as well as allowing movement Ranged
Bane ammo (against their attuned targets (Dragons, Abyssal, Basilisks, Wallasalkis), also 25% ability damage boost or 40% boost to auto-attacks) 30% Ranged
Confuse -5% for the affected target Magic
Stagger -10% for the affected target Magic
Sonic Wave 6% on your next attack Magic
Reaper necklace 0.1% per stack (3% max) Any
Offensive Ultimate Abilities (Omnipower, Meteor Strike, Onslaught, etc) 25% Any
Blisterwood weapons and Sunspear variants (against vampyres, vyrewatch, vyrelords/ladies, also chance to deal +100% damage) 50% Any

### Affinity modifiers

The following items and abilities increase the target's affinity, thereby making it easier to hit them. Only one of each can be active at once, and they stack additively with each other (i.e. using quake twice won't apply a +4 debuff, but quake with a barrelchest anchor special attack would be +6) up to a maximum of +10. Using the ability again refreshes the duration.

Effect Debuff
amount
Duration
Abilities
Quake +2 1 minute
Special attacks
Guthix staff +2 1 minute
Statius warhammer +5 1 minute
Dragon hatchet +3 1 minute
Barrelchest anchor +4 1 minute
Bone dagger +2 1 minute
Passives
(Illuminated) Bandos's Book of War +3 12 seconds

### Hit chance examples

Using Saradomin godsword (slash style) at Abyssal demon (slash weakness) with 99 attack:

• ${\displaystyle Aff=90}$
• ${\displaystyle a=F(99)+2.5*F(75)=2906}$
• ${\displaystyle d=1608+F(70)=2202}$
• ${\displaystyle H=Aff\times a/d=90\times 2906/2202=118.8\%}$

hit chance is capped at 100%, so all attacks will not miss.

On the other hand, using Sunspear (ranged) with 99 ranged in void knight armour will result in misses:

• ${\displaystyle Aff=45}$
• ${\displaystyle a=F(99)+2.5*F(78)=3041}$
• ${\displaystyle d=1608+F(70)=2202}$
• ${\displaystyle H=mod\times Aff\times a/d=1.03\times 45\times 3041/2202=62.1\%}$

For a Queen Black Dragon bossing situation, using Royal crossbow, Overload, Anguish, and Royal bolts with 99 ranged will result in misses:

• ${\displaystyle Aff=50}$
• ${\displaystyle a=F(126)+2.5*F(80)=4068}$
• ${\displaystyle d=2074+F(80)=2844}$
• ${\displaystyle H=Aff\times a/d=50\times 4068/2844=71.5\%}$

Swapping for Dragonbane bolt will provide an additive bonus to hit chance:

• ${\displaystyle H_{dbane}=H+mod=0.715+0.3=101.5\%}$

and, therefore, reaching hit cap.

## Boss armour ratings

The tables below are for quick look-up of the total armour rating of current bosses. For the affinity values to your combat style, refer to the boss's individual page. HM and CM refers to hard mode and challenge mode, respectively.

### God Wars Dungeon 1

Bosses include: Commander Zilyana, General Graardor, Kree'arra, K'ril Tsutsaroth, and Nex.

Boss F() Armour Total
Normal Mode 678 1299 1977
Hard Mode 678 1694 2372
Nex 770 1924 2694
Nex (Aod) 1212 2765 3977

### God Wars Dungeon 2

The stats shown for Vindicta are for her second phase, which are higher than the first.

Boss F() Armour Total
Gregorovic 678 1694 2372
Gregorovic (CM) 770 1924 2694
Helwyr 594 1486 2080
Helwyr (CM) 678 1694 2372
Twin Furies 594 1486 2080
Twin Furies (CM) 678 1486 2164
Vindicta 770 1924 2694
Telos 770 1924 2694

### Raids

Boss F() Armour Total
Beastmaster Durzag 1106 2458 3564
Yakamaru 1212 2765 3977

### Solo/Duo

Boss F() Armour Total
The Magister 1031 2577 3608
Araxxor 871 2458 3329
Araxxi 770 1924 2694
Har-Aken 770 1924 2694
Queen Black Dragon 770 2074 2844

### Group

Boss F() Armour Total
Chaos Elemental 579 1447 2026
Corporeal Beast 678 1694 2372
Giant mole 293 732 1025
Dagannoth Kings 564 1409 1973
Kalphite King 871 2178 3049
Kalphite Queen 594 1486 2080
Exiled Kalphite Queen 678 1694 2372
King Black Dragon 453 1132 1585
Vorago 983 2178 3161

## Update history

This information has been compiled as part of the update history project. Some updates may not be included - see here for how to help out!
• patch 12 September 2016 (Update):
• Lowered the base hit-chance bonuses from some effects:
• Statius's Warhammer special attack, 10% -> 5%
• Dragon hatchet special attack, 5% to 3%
• Barrelchest anchor special attack, 5% to 4%
• Bone dagger special attack, 5% to 2%
• Bandos'/Illuminated book of war random effect, 5% to 3%