Understanding Effect Hit Rate in Honkai: Star Rail
Effect Hit Rate (EHR) is a crucial stat in Honkai: Star Rail for Nihility characters and any unit that applies debuffs (like Freeze, Burn, Shock, or Defense Shred). The game uses a specific formula to determine if a debuff lands successfully.
The Hit Chance Formula
The actual probability of applying a debuff, known as the "Real Chance," is calculated using the following equation:
Base Chance: The percentage listed in your character's trace or skill description (e.g., Pela's Ultimate has a 100% Base Chance).
Attacker's EHR: The total Effect Hit Rate from your character's relics, light cones, and traces.
Enemy Effect RES: The innate resistance enemies have against all debuffs. High-level bosses usually have 30% or 40% Effect RES.
Debuff RES: Specific resistance against certain types of crowd control (e.g., Cocolia has high Freeze RES). This is usually 0% for general calculations unless facing specific bosses.
Common Enemy Resistance Values
Enemy Type
Typical Effect RES
Recommended EHR (for 100% Base Chance)
Small Mobs
0% – 10%
0%
Elites (Level 90+)
30%
43%
Bosses (MoC 12)
40%
67%
How to Use This Calculator
Enter the Base Chance of your character's skill. Input your current Effect Hit Rate from your stats screen. Enter the Enemy Effect RES (standard endgame bosses have 40%). The calculator will tell you exactly how likely you are to land your debuff.
function calculateHitChance() {
// 1. Get input values
var baseChanceInput = document.getElementById('baseChance').value;
var attackerEHRInput = document.getElementById('attackerEHR').value;
var enemyEffResInput = document.getElementById('enemyEffRes').value;
var debuffResInput = document.getElementById('debuffRes').value;
// 2. Validate inputs
if (baseChanceInput === "" || attackerEHRInput === "" || enemyEffResInput === "") {
alert("Please fill in the Base Chance, EHR, and Enemy Effect RES fields.");
return;
}
var baseChance = parseFloat(baseChanceInput) / 100;
var attackerEHR = parseFloat(attackerEHRInput) / 100;
var enemyEffRes = parseFloat(enemyEffResInput) / 100;
// Handle optional debuff res
var debuffRes = 0;
if (debuffResInput !== "") {
debuffRes = parseFloat(debuffResInput) / 100;
}
// 3. Calculate Real Chance
// Formula: Real = Base * (1 + EHR) * (1 – EffectRes) * (1 – DebuffRes)
var realChance = baseChance * (1 + attackerEHR) * (1 – enemyEffRes) * (1 – debuffRes);
// Cap at 0% minimum. Usually capped at 100% visually, but theoretically can go higher.
// For display purposes, we cap at 100% if it exceeds 1.
var displayChance = realChance * 100;
if (displayChance > 100) displayChance = 100;
if (displayChance 0) {
var requiredEHRDecimal = (1 / denominator) – 1;
var requiredEHRPercent = requiredEHRDecimal * 100;
// If already 100% or more, or if required is negative (meaning base stats are enough)
if (requiredEHRPercent <= 0) {
requiredEHRMsg = "You are already guaranteed to hit (0% extra EHR needed).";
} else {
requiredEHRMsg = "To guarantee a hit (100%), you need " + requiredEHRPercent.toFixed(1) + "% Total EHR.";
}
} else {
requiredEHRMsg = "Impossible to hit (Enemy has 100% Resistance).";
}
// 5. Display Results
var resultBox = document.getElementById('resultBox');
var finalChanceDisplay = document.getElementById('finalChance');
var requiredDisplay = document.getElementById('requiredEHRDisplay');
resultBox.style.display = 'block';
finalChanceDisplay.innerHTML = displayChance.toFixed(2) + "%";
// Add color coding for success chance
if (displayChance >= 100) {
finalChanceDisplay.style.color = "#00b894"; // Green
} else if (displayChance >= 80) {
finalChanceDisplay.style.color = "#fdcb6e"; // Yellow/Orange
} else {
finalChanceDisplay.style.color = "#ff7675"; // Red
}
requiredDisplay.innerHTML = requiredEHRMsg;
}