Ability damage

In combat, ability damage is a number based on your skills, weapons, and armour, which is used by almost all abilities to determine how strongly they can hit. Ability damage is affected by damage-boosting items. It is closely related to the auto-attack damage shown in the combat interface, but it varies in notable and significant ways.

Ability damage can be viewed in the abilities tab of offensive stats, under the loadout tab of the worn equipment interface.

Abilities use the player's ability damage to determine their maximum hit. In general, the damage is multiplied by a particular number that is stated on the interface (for example, Slice's maximum hit is $120A$). A normal ability hit will deal between 20% to 100% of its maximum damage. If the ability deals between 95% to 100% of its maximum damage, it is a critical hit.

Calculating ability damage

Magic

For magic, your ability damage $D$ is:

$D = \begin{cases} 2.5 M + \min(9.6 t_m,s_m) + b & \text{for main-hand}\\ 1.25 M + \min(4.8 t_o,s_o) + 0.5b & \text{for off-hand}\\ 3.75 M + \min(14.4 t_m,s_m) + 1.5b & \text{for two-hand}\\ \end{cases}$

Where:

• $M$ is your level in Magic, including boosts
• $t_m$ is the tier of your main-hand weapon
• $t_o$ is the tier of your off-hand weapon
• $s_m$ is the damage of your main-hand spell
• $s_o$ is the damage of your off-hand spell
• $b$ is the sum of all Magic bonuses from armour and jewellery.

Main- and off-hand spell damage can be found by mousing over the damage value in Offensive Stats. For spell damage with a staff, take it instead as 1.5 times the spell damage from a wand of equal level.

Decimal results are rounded down. When dual-wielding, the results for main- and off-hand ability damage are to be added together.

Melee

For melee, your ability damage $D$ is

$D = \begin{cases} 2.5 S + d_m \times s_m + b & \text{for main-hand}\\ 1.25 S + d_o \times s_o + 0.5b & \text{for off-hand}\\ 3.75 S + d_m \times s_m + 1.5b & \text{for two-hand}\\ \end{cases}$

Where:

• $S$ is your level in Strength, including boosts
• $d_m$ is the damage of your main-hand weapon
• $d_o$ is the damage of your off-hand weapon
• $s_m$ and $s_o$ are multipliers, based on the speed of your main- and off-hand weapons, that serve to localise weapon damage:

  $s={\begin{cases}{\frac {96}{149}}\approx 0.644295&{\text{Average}}\\{\frac {192}{245}}\approx 0.783673&{\text{Fast}}\\1&{\text{Fastest}}\\\end{cases}}$

• $b$ is the sum of all Strength bonuses from armour and jewellery.

Decimal results are rounded down. When dual-wielding, the results for main- and off-hand ability damage are to be added together.

Ranged

For ranged, your ability damage $D$ is:

$D = \begin{cases} 2.5 R + \min(9.6 t_m,d_a) + b & \text{for main-hand}\\ 1.25 R + \min(4.8 t_o,0.5d_a) + 0.5b & \text{for off-hand}\\ 3.75 R + \min(14.4 t_m,1.5d_a) + 1.5b & \text{for two-hand}\\ \end{cases}$

Where:

• $R$ is your level in Ranged, including boosts
• $t_m$ is the tier of your main-hand weapon
• $t_o$ is the tier of your off-hand weapon
• $d_a$ is the damage of your ammunition
• $b$ is the sum of all Ranged bonuses from armour and jewellery.

Shieldbows count as main-handed for the calculation. If using throwing weapons or a bow that generates its own arrows, ability damage is calculated in the same fashion as with melee weapons.

Decimal results are rounded down. When dual-wielding, the results for main- and off-hand ability damage are to be added together.

Boosting ability damage

Prayer

Prayers increase your ability damage by a set percentage, which can be found on the Prayer page. Prayers do not affect the damage of bleed abilities.

Potions

The effect of potions is twofold.

• Potions increase your visible Magic, Strength and Ranged levels, which are used during the ability damage calculation.
• Each boosted level provides $(4-8)$ extra damage to each hit you deal. Precise, Equilibrium, and Biting perks affect this extra damage. (With Precise 4 and Equilibrium 2, this becomes $(4.69-7.93)$ extra damage.) This extra damage is not affected by prayer multipliers but is affected by all other multipliers. This extra damage has no effect on bleed abilities.

Other boosts

There are many miscellaneous items and situations that can boost your ability damage. If multiple percentage multipliers stack, they will stack in a multiplicative fashion. All of them work on bleeds except for Void Knight equipment and the slayer helmet and equivalents.

• Black mask, Focus sight, Hexcrest, Full slayer helmet and Slayer helmet boost your damage by 12.5% when on a Slayer task for a particular creature. This rises with Slayer helmet upgrades up to a maximum of 14.5% damage increase with the Corrupted slayer helmet.
• Void Knight armour and its superior variant boost damage for one combat style by 5-7% respectively.
• Salve amulet and Salve amulet (e) boosts your ability damage by 15% and 20% respectively against undead creatures.
• Stone of Jas boosts damage from 3–6% within a certain range of the Glacor cave.
• Ferocious ring boosts damage by 4% when on a slayer task in Kuradal's Dungeon.
• Kethsi ring boosts damage against Metal dragons by 4%, and 8% when in Kuradal's Dungeon.
• Fremennik sea boots 4 boosts ability damage by 5% when worn while fighting any of the Dagannoth Kings.
• Balmung boosts ability damage by 12.5% and 7.5% against Dagannoths and the Dagannoth Supreme respectively.
• Upgraded Balmung boosts ability damage by 22.5% and 17.5% against Dagannoths and the Dagannoth Supreme respectively.
• Bane ammunition increases ability damage by 25% against appropriate monsters.
• TokKul-Zo increases ability damage by 10% against TzHaar creatures.
• Keris increases damage by 33% against Kalphites, and occasionally increases it by 200%.
• Brine sabre and Brackish blade increase damage against 'rum'-pumped crabs.
• Silverlight and Darklight increase ability damage by a scaling of 25-124% against most demons. The exact damage bonus is based on your base Attack and Strength, and the monster's base Defence.
• Upgraded Darklight increase ability damage by a scaling of 50-149% against most demons.
• Using the portal to the King Black Dragon in the Lava Maze increases damage by 10%.
• Ancient Magicks increase damage by 100% against Muspahs.
• Fire spells deal 50% extra damage to Ice strykewyrms and Glacors.