Runescape Combat Calculator – Calculator City

Damage	Probability
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What is a RuneScape Combat Calculator?

A runescape combat calculator is a vital tool for players of Old School RuneScape (OSRS) who want to maximize their combat efficiency. It takes your character’s stats—such as Attack and Strength levels—along with your gear, active prayers, and potions, to predict your combat performance. The primary outputs are your Damage Per Second (DPS), maximum possible hit (“max hit”), and your accuracy against a specific target. By using a runescape combat calculator, you can make informed decisions about which gear to buy, which prayers to use, and how to train your account for optimal results in both Player vs. Monster (PvM) and Player vs. Player (PvP) scenarios. This avoids costly trial-and-error in-game. For more advanced setups, consider our advanced gear comparison tool.

The RuneScape Combat Calculator Formula

The core of any OSRS runescape combat calculator involves a series of formulas defined by the game’s mechanics. While complex, they can be broken down into a few key steps: calculating your effective levels, determining your maximum rolls, and then finding the hit chance.

1. Effective Strength & Max Hit Formula

Your max hit is not based on your visible strength level alone. It’s calculated using an “Effective Strength Level”.

Effective Strength = floor((Strength Level + Potion Boost) * Prayer Multiplier) + Style Bonus + 8

Once you have the effective strength, the max hit is calculated:

Max Hit = floor(0.5 + Effective Strength * (Equipment Strength Bonus + 64) / 640)

2. Effective Attack & Accuracy Formula

Similarly, your accuracy depends on your “Effective Attack Level” and the target’s defence.

Effective Attack = floor((Attack Level + Potion Boost) * Prayer Multiplier) + Style Bonus + 8

This is then used to find your Attack Roll:

Max Attack Roll = Effective Attack * (Equipment Attack Bonus + 64)

The target has a corresponding Defence Roll. The game compares these two rolls to see if you land a hit. Our calculator simplifies this into a final accuracy percentage. For a deep dive into defensive calculations, see our guide on understanding defence mechanics.

Variables Table

Key variables used in the runescape combat calculator.
Variable	Meaning	Unit	Typical Range
Strength/Attack Level	Your base skill level.	Level	1 – 99
Potion Boost	Temporary skill increase from potions.	Level Points	+3 to +26
Prayer Multiplier	Percentage-based boost from prayers.	Multiplier	1.05x – 1.23x
Equipment Bonus	The sum of bonuses from your gear.	Stat Points	0 – 250+
Weapon Speed	Time between attacks in game ticks.	Ticks	2 – 7

Practical Examples

Example 1: Mid-Level Slayer Task

Imagine a player with 75 Attack and 75 Strength using a Dragon Scimitar against a monster with 70 Defence.

Inputs: Attack: 75, Strength: 75, Prayer: Piety (20% Atk, 23% Str), Potion: Super Combat (15%+5), Weapon Speed: 4, Equipment Atk: +100, Equipment Str: +90, Target Def Level: 70, Target Def Bonus: +50
Results: This setup would yield a high DPS, making it efficient for slayer tasks. The runescape combat calculator shows the significant boost from using Piety and a Super Combat Potion.

Example 2: Bossing Setup

A high-level player with 99 in combat stats is fighting a boss with very high defence.

Inputs: Attack: 99, Strength: 99, Prayer: Piety, Potion: Super Combat, Weapon Speed: 4, Equipment Atk: +150, Equipment Str: +140, Target Def Level: 250, Target Def Bonus: +150
Results: Even with maxed stats, the high defence of the boss reduces accuracy. The runescape combat calculator helps determine if gear that increases accuracy (like a Ghrazi rapier) is better than gear that only increases strength (like a Blade of saeldor), even if the max hit is slightly lower. This is a key part of optimizing for high-level PvM, something we cover in our bossing gear guide.

How to Use This RuneScape Combat Calculator

Enter Your Stats: Input your character’s base Attack and Strength levels.
Select Boosts: Choose any potions and prayers you are using from the dropdown menus. The calculator will automatically apply the correct percentage or flat boosts.
Input Gear Bonuses: Go to your in-game equipment stats screen and enter the total Attack Bonus and Strength Bonus. Make sure to use the bonus for the attack style you have selected (e.g., Slash bonus for a scimitar).
Set Target Information: Enter the Defence level and appropriate Defence bonus of your target. You can find this information on the OSRS Wiki.
Review Results: The calculator will instantly update your DPS, Max Hit, and Accuracy. Use this data to compare different setups. Don’t forget to check our training guide for the best places to use your new setup.

Key Factors That Affect Combat Performance

Strength Bonus: Directly increases your max hit. Every few points of strength bonus typically add 1 to your max hit.
Attack Bonus: Increases your accuracy. This is crucial against high-defence monsters where hitting consistently is more important than hitting high.
Weapon Speed: A faster weapon attacks more often, which can lead to higher DPS even if the max hit is lower. This is a fundamental concept of DPS.
Prayer and Potions: These provide the largest temporary boosts to your combat stats and are essential for efficient combat. Forgetting to re-pot can drastically lower your DPS.
Attack Style: Using the correct attack style to exploit a monster’s weakness (e.g., using Crush against a heavily armored monster) significantly increases accuracy.
Special Gear: Items like the Slayer Helmet (on task) or Void Knight equipment provide percentage-based damage and accuracy boosts that are more powerful than flat stat bonuses. Understanding these is key to true optimization, as detailed in our special gear analysis.

Frequently Asked Questions (FAQ)

1. Why is my DPS so low even with a high max hit?: Your accuracy is likely low. DPS is a combination of how hard you hit and how often you hit. If your target has high defence, you’ll hit a lot of zeros, bringing your average damage down significantly. Use the runescape combat calculator to see if boosting your Attack bonus helps.
2. Does this calculator work for Ranged or Magic?: This specific calculator is designed for melee. Ranged and Magic combat use different formulas, particularly for calculating max hit and effective levels. We plan to release dedicated calculators for them soon.
3. How do I find my equipment bonus?: In-game, click the “Worn Equipment” icon. At the bottom, click the “View equipment stats” button. This screen shows all your combat bonuses, including “Melee strength” and “Attack bonus” for each style.
4. Is a faster weapon always better?: Not always. A very fast weapon (like daggers, speed 2) might have a low max hit, resulting in lower DPS than a slightly slower but harder-hitting weapon (like a scimitar, speed 4). The runescape combat calculator is the best way to compare them directly.
5. What does “Effective Level” mean?: It’s a temporary, calculated level used in the damage formulas. It combines your base skill level with boosts from potions, prayers, and your attack style to determine your “true” power for a single calculation.
6. How accurate is this calculator?: This calculator uses the most up-to-date, community-verified formulas for OSRS combat. The results should be identical to what you would find in-game, assuming all inputs are correct.
7. Why isn’t my special attack (spec) included?: Special attacks often have unique damage and accuracy modifiers. This calculator focuses on sustained DPS from basic attacks. A separate tool would be needed to model the burst damage from specs.
8. Does this calculator account for monster weakness?: Yes, indirectly. A monster’s weakness is reflected in its defence bonuses. For example, a dragon is weak to Stab, so its “Stab defence” bonus will be much lower than its “Slash defence” bonus. By entering the correct defence bonus for your attack style, you are accounting for its weakness.

Related Tools and Internal Resources

Enhance your gameplay with our other calculators and guides:

Advanced Gear Comparison Tool: Compare multiple gear setups side-by-side.
Understanding Defence Mechanics: A deep dive into how defensive stats work.
Bossing Gear Progression Guide: What to buy next for your PvM journey.
AFK Combat Training Guide: The best low-effort methods to level up.
Special Gear Analysis: When to use Void, Salve, or a Slayer Helm.
Prayer Flicking Simulator: Practice your prayer timing to save supplies.

RuneScape Combat Calculator (OSRS Melee DPS)

DPS vs. Target Defence Level

Hit Distribution Table