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 in the abilities tab of offensive damage, under the loadout tab of the gear interface.

Magic
$$ d_{m} = \begin{cases} {\color{white}} 2.5 l_m + \min\{9.6 l_{mh},d_{ms}\} + b & \mbox{for main-hand}\\ 1.25 l_m + \min\{4.8 l_{oh},d_{os}\} + 0.5b & \mbox{for off-hand}\\ 3.75 l_m + \min\{14.4 l_{mh},d_{ms}\} + 1.5b & \mbox{for two-hand}\\ \end{cases} $$

Where:
 * $$d_m$$ is your damage with magic abilities.
 * $$l_m$$ is your level in Magic, including boosts.
 * $$l_{mh}$$ is the required level to use the weapon in your main-hand.
 * $$l_{oh}$$ is the required level to use the weapon in your off-hand.
 * $$d_{ms}$$ is the stated damage of your main-hand spell.
 * $$d_{os}$$ is the stated 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
$$ d_{w} = \begin{cases} {\color{white}} 2.5 l_s + d_{mh}s_{mh} + b & \mbox{for main-hand}\\ 1.25 l_s + d_{oh}s_{oh} + 0.5b & \mbox{for off-hand}\\ 3.75 l_s + d_{mh}s_{mh} + 1.5b & \mbox{for two-hand}\\ \end{cases} $$

Where:
 * $$d_w$$ is your damage with warrior abilities.
 * $$l_s$$ is your level in Strength, including boosts.
 * $$d_{mh}$$ is the stated damage of your main-hand weapon.
 * $$d_{oh}$$ is the stated damage of your off-hand weapon.
 * $$s_{mh}$$ and $$s_{oh}$$ are multipliers, based on the speed of your main- and off-hand weapons, that serve to localise weapon damage:
 * For Average weapons, this is 96/149.
 * For Fast weapons, this is 960/1225.
 * For Fastest weapons, this is 1.
 * $$b$$ 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
$$ d_{r} = \begin{cases} {\color{white}} 2.5 l_r + \min\{9.6 l_{mh},d_a\} + b & \mbox{for main-hand}\\ 1.25 l_r + \min\{4.8 l_{oh},0.5d_a\} + 0.5b & \mbox{for off-hand}\\ 3.75 l_r + \min\{14.4 l_{mh},1.5d_a\} + 1.5b & \mbox{for two-hand}\\ \end{cases} $$

Where:
 * $$d_r$$ is your damage with ranged abilities.
 * $$l_r$$ is your level in Ranged, including boosts.
 * $$l_{mh}$$ is the required level to use the weapon in your main-hand.
 * $$l_{oh}$$ is the required level to use the weapon in your off-hand.
 * $$d_a$$ is the stated 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.

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 a random +4-8 extra damage. However, this occurs after any other multipliers such as ability and prayer multipliers, so it simply adds  to each hit you deal. This extra damage has no effect on bleed abilities.

Other boosts
There are many miscellaneous items and situations that can boost your ability damage. 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 ability damage by 12.5% when on a Slayer task.
 * Salve amulet and Salve amulet (e) boosts your ability damage by 15% and 20% respectively against undead creatures.
 * Stone of Jas boosts ability damage from 3–6% within a certain range of the ritual site.
 * Ferocious ring boosts ability damage by 4% when on a task 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% against Dagannoths.
 * 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 by 40% against 'rum'-pumped crabs.
 * Silverlight and Darklight double ability damage against demons.
 * Using the portal to the King Black Dragon in the Lava Maze increases ability damage by 10%.
 * Ancient Magicks increase damage by 100% against Muspahs.

Use with abilities
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 .) 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.