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 levels, equipment or buffs) can change hit chance.

In typical PvM combat, hit chance affects Damage Potential, which is a calculated statistic that determines how much damage a player's abilities will do. If a player has between 1% and 100% hit chance, their damage is scaled accordingly. If a player has under 1% hit chance, they will miss all their attacks.

In the target information panel, a player can see their hit chance against the enemy. This value will determine how much of the damage potential can be dealt against them. For example, if the basic attack ability can deal a maximum of 1000 damage and the player has a 50% hit chance against the target, the ability will only be able to deal 50% of its damage potential resulting in a maximum of 500 damage.

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.

Player versus player hit chance

Rather than the damage potential system that PvM uses, in PvP, 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. That is, in PvP, an ability either does damage as if it had full 100% damage potential, or the ability doesn't do any damage at all.

Sources that bypass hit chance

There are a number of damage sources that bypass hit chance mechanics and the associated damage potential:

• A large number of boss mechanics
• Perks:
  • Crackling
  • Aftershock
• Poison
• Necromancy's conjured spirits
• Split soul incantation
• The Eldritch crossbow's special attack, Split Soul
• Damage over time from normal and greater Sunshine, normal and greater Death's Swiftness, and the Zaros godsword's special attack
• The healing induced damage caused by the Blood reaver familiar passive effect

The hit chance formula

In non-PvP combat, hit chance impacts how much damage is applied to a target, given your accuracy, the armour of your opponent, and the style you are using.

Your hit chance $H$ (as a percentage) is calculated as:

$H=\mathrm{A}\mathrm{f}\mathrm{f}\times \frac{a}{d}+m$

Where:

• $\mathrm{A}\mathrm{f}\mathrm{f}$ is affinity
• $a$ is your accuracy
• $d$ is the target's armour rating
• $m$ is an additive modifier to hit chance. Below this term is omitted when there are no modifiers active

The hit chance is capped at 100%.

Affinity

Main article: 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) or when using necromancy
• 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. Necromancy always uses the middle affinity value for monsters with custom values.

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.

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's special attack would be +6), up to a maximum of +10. Using the ability again refreshes the duration.

Effect	Debuff amount	Duration	Adrenaline cost
Abilities
Quake	+2	1 minute	15%
Special attacks
Claws of Guthix (Guthix staff)	+2	1 minute	25%
Obliterate (Statius warhammer)	+5	1 minute	35%
Clobber (Dragon and Crystal hatchet)	+3	1 minute	30%
Sunder (Barrelchest anchor)	+4	1 minute	50%
Backstab (Bone dagger)	+2	1 minute	75%
Passive effects
(Illuminated) Bandos's Book of War	+3	12 seconds	N/A

Accuracy

A players total accuracy stat is the sum of their level bonus $L$ and weapon tier bonus $T$. Both of these values involve the formula $f(x)=\frac{1}{1250}{x}^3+4x+40$. If the player has level $\ell$ in the relevant attack skill (Attack, Ranged, Magic, or Necromancy), their level bonus is just $L=f(\ell )$ (rounded down). For example, a player with level 99 Attack and no weapon equipped will have (rounded) accuracy $f(99)=1212$. Temporary boosts such as overloads and stat-boosting prayers will affect this value. Since the formula is exponential at higher levels $+1$ level changes the accuracy more than at lower levels.

The level-based bonus for a player with level 99 attack/magic/ranged/necromancy, and for 120 necromancy are shown below for various boosts.

Effects	Attack/magic/ranged level $\ell$	Level accuracy bonus $L=f(\ell )$
/ / /	99	1,212
/ / /	109	1,512
/ / /	111	1,578
	116	1,753
	118	1,826
	120	1,902
+ / / /	126	2,144
+ / / /	128	2,230
+ / / /	130	2,317
+ / / /	132	2,407
+ / / + / /	140	2,795
+ / / + / /	142	2,898

Effects	Necromancy level $\ell$	Level accuracy bonus $L=f(\ell )$
	120	1,902
	130	2,317
	132	2,407
	141	2,846
	143	2,951
	145	3,058
+	151	3,398
+	153	3,517
+	155	3,639
+	157	3,763

A weapon of tier $t$ accuracy gives an accuracy boost of $T=2.5f(t)$. For example, if a player has 99 Ranged and is using a tier 92 bow, they will have an accuracy of 3,789 (which is $f(99)+2.5f(92)$ rounded down. If a potion temporarily raises their ranged level to 120, they will have temporarily have an accuracy value of 4,360 (which is $f(120)+2.5f(92)$ rounded down).

Weapon tier $t$	Weapon accuracy bonus $T=2.5f(t)$
70	1,486
75	1,694
80	1,924
85	2,178
90	2,458
92	2,577
95	2,764
99	3,031
100	3,100

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) or wearing non-Necromancy armour when using Necromancy, will result in an accuracy penalty that is 3/2 (x1.5) the item's armour stat. Wearing any other wrong style of armour (if using Melee, this is Magic or Necromancy) 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%
Obsidian helmets (Only while in the TzHaar City or the TzekHaar Front)	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%
Dragon scimitar's special attack, Draconic Slash (slash weapons only)	1.25	25%

Armour rating

The target's armour rating $d$ is the sum of their armour and armour bonus granted by their Defence level, rounded down.

The armour bonus granted by Defence level is calculated using the same function as above: $f(x)=\frac{1}{1250}{x}^3+4x+40$ where $x$ is the Defence level.

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	1,299	1,977
Hard Mode	678	1,694	2,372
Nex	770	1,924	2,694
Nex (Aod)	1,212	2,765	3,977

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	1,694	2,372
Gregorovic (CM)	770	1,924	2,694
Helwyr	594	1,486	2,080
Helwyr (CM)	678	1,694	2,372
Twin Furies	594	1,486	2,080
Twin Furies (CM)	678	1,486	2,164
Vindicta	770	1,924	2,694
Telos	770	1,924	2,694

Raids

Boss	f()	Armour	Total
Beastmaster Durzag	1,106	2,458	3,564
Yakamaru	1,212	2,765	3,977

Solo/Duo

Boss	f()	Armour	Total
The Magister	1,031	2,577	3,608
Araxxor	871	2,458	3,329
Araxxi	770	1,924	2,694
Har-Aken	770	1,924	2,694
Queen Black Dragon	770	2,074	2,844
Raksha	871	2,178	3,049

Group

Boss	f()	Armour	Total
Chaos Elemental	579	1,447	2,026
Corporeal Beast	678	1,694	2,372
Giant mole	293	732	1,025
Dagannoth Kings	564	1,409	1,973
Kalphite King	871	2,178	3,049
Kalphite Queen	594	1,486	2,080
Exiled Kalphite Queen	678	1,694	2,372
King Black Dragon	453	1,132	1,585
Vorago	983	2,178	3,161

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.

Item	Addition	Combat Style
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
Blisterwood weapons and Sunspear variants (against vampyres, vyrewatch, vyrelords/ladies, also chance to deal +100% damage)	50%	Any

Hit chance examples

Using Saradomin godsword (slash style) at abyssal demons (a monster with slash weakness) with level 99 Attack:

• $\mathrm{A}\mathrm{f}\mathrm{f}=90$
• $a=\lfloor f(99)+2.5\times f(75)\rfloor =2,905$
• $d=\lfloor 1,608+f(70)\rfloor =2,202$
• $H=\mathrm{A}\mathrm{f}\mathrm{f}\times a/d=90\times 2,905/2,202\approx 118.7\%$

As the hit chance is capped at 100%, no attacks will miss and abilities will hit to their full potential.

On the other hand, using Sunspear (ranged) with level 99 Ranged in void knight armour will result in a hit chance lower than 100%:

• $\mathrm{A}\mathrm{f}\mathrm{f}=45$
• $a=1.03\times \lfloor f(99)+2.5\times f(78)\rfloor \approx 3,132$
• $d=\lfloor 1,608+f(70)\rfloor =2,202$
• $H=\mathrm{A}\mathrm{f}\mathrm{f}\times a/d\approx 45\times 3,132/2,202\approx 64.0\%$

As a result, an ability that would normally hit for 1,000 damage will only deal approximately 640 damage to the target.

For a Queen Black Dragon bossing situation, using royal crossbow, overload, Anguish, and royal bolts with level 99 Ranged will result in lower than 100% hit chance:

• $\mathrm{A}\mathrm{f}\mathrm{f}=50$
• $a=\lfloor f(126)+2.5\times f(80)\rfloor =4,068$
• $d=\lfloor 2,074+f(80)\rfloor =2,843$
• $H=\mathrm{A}\mathrm{f}\mathrm{f}\times a/d=50\times 4,068/2,843\approx 71.5\%$

Swapping for dragonbane bolts will provide an additive bonus to hit chance:

• $H=\mathrm{A}\mathrm{f}\mathrm{f}\times a/d+m\approx 0.715+0.3=101.5\%$

and, therefore, reaching the accuracy cap.

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 29 July 2024 (Update):
  • Corrected an accuracy miscalculation that was introduced with the previous week's update.

• patch 4 March 2024 (Update):
  • Damage Potential
    • Replaced the 'roll to hit' system with the 'damage potential' system for Melee, Ranged and Magic combat against NPCs.
    • Removed a number of hidden buffs that increased your hit chance when using special attacks or ultimate abilities.
    • Reduced the minimum hit chance required to damage an NPC under the new system.
      • 25% → 1%

• patch 7 August 2023 (Update):
  • Removed a workaround for high-defence monsters that would halve the stats of any taggable monster.

• patch 1 September 2020 (Update):
  • Hit chance modifiers are now recalculated right after the 'Stagger' spell, 'Confuse' spell, or the Sandstorm Camel Debuff hits the target in PvP.

• 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%