OSRS Accuracy and Hit Chance Explained: How to Calculate if You'll Hit
Understand OSRS accuracy and hit chance calculation. Learn how attacker and defender rolls determine whether your attack lands, and how equipment bonuses and prayer affect accuracy.
Related Calculators
- OSRS Dry CalculatorCalculate your probability of still being dry (or having received a drop) at any Old School RuneScape drop rate and kill count.
- OSRS Combat CalculatorCalculate your Old School RuneScape combat level from your Attack, Strength, Defence, Hitpoints, Ranged, Magic, and Prayer levels.
- OSRS Combat Level CalculatorCalculate OSRS combat level from Attack, Strength, Defence, Hitpoints, Prayer, Ranged, and Magic.
- OSRS DPS CalculatorCalculate manual-mode Old School RuneScape DPS for melee or ranged setups using attack rolls, defence rolls, max hit, weapon ticks, and hit chance.
- OSRS Max Hit CalculatorCalculate a manual melee or ranged maximum hit from level, boost, prayer, style, void, equipment bonus, and damage multipliers.
- OSRS ToA Loot CalculatorCalculate cumulative ToA purple chance, expected unique chests, target-item chance, expected value, raids required, and GP per hour.
How OSRS Accuracy Works
Every melee, ranged, or magic attack in OSRS involves two hidden random rolls: 1. Attacker's accuracy roll — a random number from 0 to the player's max accuracy value 2. Defender's defence roll — a random number from 0 to the monster's max defence value
If the attacker's roll strictly exceeds the defender's roll, the attack hits. Otherwise, it misses (dealing 0 damage).
The Accuracy Formula
Effective Attack Level = floor(Attack Level × Prayer Multiplier) + Stance Bonus + 8
Max Accuracy Roll = Effective Attack Level × (Equipment Attack Bonus + 64)
Max Defence Roll = Effective Defence Level × (Equipment Defence Bonus + 64)
Hit Chance (if Attacker > Defender): Hit Chance = 1 − (Defender's Max + 2) ÷ (2 × Attacker's Max + 1)
Hit Chance (if Defender ≥ Attacker): Hit Chance = Attacker's Max ÷ (2 × Defender's Max + 1)
Worked Example
Player: 80 Attack, Piety (×1.20), Accurate stance (+3), +80 stab bonus Target: Effective Defence 100, +80 stab defence
Effective Attack = floor(80 × 1.20) + 3 + 8 = 96 + 3 + 8 = 107 Attacker's Max = 107 × (80 + 64) = 107 × 144 = 15,408
Defender's Max = 100 × (80 + 64) = 100 × 144 = 14,400
Since 15,408 > 14,400 (Attacker > Defender): Hit Chance = 1 − (14,400 + 2) ÷ (2 × 15,408 + 1) = 1 − 14,402 ÷ 30,817 = 1 − 0.4674 = 53.3% hit chance
Equipment Attack Styles and Their Bonus Slots
Your attack bonus depends on your chosen attack style (stab, slash, or crush for melee) and your equipment's corresponding bonus:
Always attack using the style that matches the monster's weakness — a 10% accuracy improvement from exploiting weakness can translate to significantly more DPS.
Practical Accuracy Benchmarks
For common bossing:
Magic Accuracy: Different System
For magic, the accuracy roll uses Magic Attack Bonus from equipment, but magic has a different effective level formula:
Effective Magic Level = floor(Magic Level × Prayer) + Stance + 8
Mage hit chance follows the same roll-vs-roll system, but splash rate also depends on your spell's base accuracy rate — some spells have innate accuracy modifiers.
Related Guides
- How OSRS DPS Is Calculated: Attack Bonus, Strength, and PrayerUnderstand how OSRS damage per second is calculated from attack speed, accuracy, max hit, and prayer bonuses. Covers the effective level, roll, and hit damage formulas.
- OSRS Attack Speed and Game Ticks: How Tick-Based Combat WorksUnderstand OSRS game ticks and attack speed. Every action in OSRS happens in 0.6-second tick intervals, and weapon speed determines how many ticks between attacks.
- OSRS Drop Rate Probability: How to Use a Drop Rate CalculatorLearn to use OSRS drop rate probability calculations to find your dry streak odds, time to 50% chance, and cumulative probability at any kill count.
- OSRS Combat Level Formula: How Your Combat Level Is CalculatedCalculate your OSRS combat level from your stats. Covers the combat level formula for melee, ranged, and magic combat styles, and how Prayer and Hitpoints contribute.
Frequently Asked Questions
- How is OSRS hit chance calculated?
- Hit chance depends on whether your max accuracy roll exceeds the defender's max defence roll. If Attacker's max > Defender's max: Hit Chance = 1 − (Def Max + 2)/(2 × Atk Max + 1). If Defender ≥ Attacker: Hit Chance = Atk Max / (2 × Def Max + 1). The calculation uses effective levels incorporating prayer and stance bonuses.
- How does prayer affect OSRS accuracy?
- Prayer multiplies your effective attack level before it's used in the accuracy roll. Piety multiplies attack by ×1.20, effectively adding 20% to your attack level for hit chance calculations. At 80 Attack with Piety, you effectively have 96 attack before stance bonus.
- What is the highest possible hit chance in OSRS?
- Hit chance approaches but never reaches 100% mathematically. In practice, against monsters with very low defence (like low-level slayer monsters), hit chance can be 95%+ with decent equipment. Against high-defence bosses like Vorkath, even maxed players typically achieve 80–90% hit chance.
- Does the attack style (stab/slash/crush) matter?
- Yes — monsters have different defence values for each attack style. Attacking a monster with its weak style can be 20–30% more accurate than its resistant style. Always check the OSRS Wiki's monster stats and use the appropriate attack style for meaningful DPS improvement.
Last updated 7/28/2026