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 high they can hit. Ability damage has different formulas for each combat style, and is affected by prayers and 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.

Magic
$$damage_{magic} = 1.5 \times magic + \min(9.6 \times mlvl,spell) + 5.2 \times olvl + armour$$


 * magic is your Magic skill level, including boosts. If you are only using a main hand weapon, 1.5 changes to 1.
 * mlvl is the required level to use the weapon in your main hand (or two-handed).
 * spell is the spell damage of the spell you are using.
 * olvl is the required level to use the weapon in your off hand (or two-handed).
 * armour is the amount of bonus damage you get from wearing power armour. However, if you are using a two-handed weapon or only a main hand weapon, only the main hand bonus will be added. If dual wielding, both main hand and off hand will be added.

Melee
$$damage_{melee} \approx 1.5 \times str + mdmg \times mspeed + odmg \times ospeed + armour$$


 * str is your Strength skill level, including boosts. If you are only using a main hand weapon, 1.5 changes to 1.
 * mdmg and odmg are the stated damage from your main and off hand weapons, respectively.
 * mspeed and ospeed are multipliers based on the speed of your weapon:
 * For Average weapons, this is 0.65.
 * For Fast weapons, this is 0.7875.
 * For Fastest weapons, this is 1.
 * armour is the amount of bonus damage from wearing power armour. If you are only using a main hand weapon, this is only the main hand damage. If you are using a two-handed weapon or dual wielding, this is main hand and off hand damage combined.

Ranged
$$damage_{ranged} = 1.5 \times ranged + \min(9.6 \times mlvl,ammo) + 4.8 \times olvl + armour$$


 * ranged is your Ranged skill level, including boosts. If you are only using a main hand weapon, 1.5 changes to 1.
 * mlvl is the required level to use the weapon in your main hand (or two-handed).
 * ammo is the spell damage of the ammunition you are using.
 * olvl is the required level to use the weapon in your off hand (or two-handed).
 * armour is the amount of bonus damage you get from wearing power armour. If you are only using a main hand weapon, this is only the main hand damage. If you are using a two-handed weapon or dual wielding, this is main hand and off hand damage combined.

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: for one, it increases your visible Magic, Strength and Ranged levels, so that small amount is added to your ability damage at the beginning. In addition, each boosted level provides 8 extra damage. However, this occurs after any other multipliers including ability, critical hit and prayer multipliers, so it essentially just adds  to your damage. 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 armour 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.
 * Ferocious ring boosts ability damage by 4% when on a task in Kuradal's Dungeon.
 * Balmung boosts ability damage by 45% against Dagannoths.
 * Bane ammunition increases ability damage by 18.75% 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%.

Abilities
Abilities use the ability damage number to determine their max hit. In general, the damage is multiplied by a particular number that is stated on the interface (for example, Assault's maximum hit is .) As mentioned earlier, the potion boost is then added to this. A non-critical hit (with the exception of bleeds and Unload/Frenzy) will hit between 33% and 100% of its maximum damage. Critical hits will hit between 100% and 105% damage.