Standard Ball
Great Ball
Ultra Ball
Premier Ball
Net Ball (Bug/Water)
Dive Ball (Underwater)
Repeat Ball (Caught Before)
Timer Ball (Turns)
Luxury Ball
Nest Ball (Low Level)
Lure Ball (Fishing)
Quick Ball (Start)
Dusk Ball (Night)
Heal Ball
Beast Ball
Understanding the Catch Rate Calculator (Gen 1)
The Catch Rate Calculator (Gen 1) is designed to estimate the probability of successfully catching a wild Pokémon in the original generation of Pokémon games (Red, Blue, Yellow). The catch mechanics in these games were relatively simple, and this calculator helps demystify the formula used to determine your chances.
How it Works:
The core of the calculation involves several factors:
Target Pokémon Level: The level of the wild Pokémon you are trying to catch. Higher levels generally make Pokémon harder to catch.
Your Pokémon Level: While not directly in the Gen 1 formula, it's included for context as player skill and experience are involved. The calculator primarily focuses on the target's stats and conditions.
Base Catch Rate: Each Pokémon species has a unique base catch rate assigned to it, ranging from 3 (legendary Pokémon) to 255 (common Pokémon). This is a fundamental value determining the Pokémon's inherent difficulty to capture.
Current HP: The remaining hit points of the wild Pokémon. The lower the HP, the higher your catch chance.
Max HP: The maximum hit points of the wild Pokémon. This is used to calculate the HP factor.
Status Condition: A status ailment (like Sleep, Freeze, Poison, Burn, or Paralysis) significantly increases your catch rate.
Ball Type Multiplier: Different Poké Balls have varying effectiveness. Standard Poké Balls have a multiplier of 1.0, while more advanced balls like Ultra Balls or specialized balls (e.g., Net Ball, Dusk Ball) offer higher multipliers, boosting your chances considerably.
The Formula (Simplified):
The Gen 1 catch formula can be represented in stages:
HP Factor: Calculated based on current HP and max HP. A lower percentage of remaining HP results in a higher factor.
Status Factor: A multiplier applied if the Pokémon has a status condition.
Ball Factor: The multiplier provided by the chosen Poké Ball.
Final Modifier: These factors are combined with the Pokémon's base catch rate to determine a final "shake" value. The game then checks how many times the Poké Ball shakes before closing. Three shakes mean a successful catch; fewer shakes mean the Pokémon breaks free.
This calculator provides a simplified output of the estimated catch percentage based on these inputs. It aims to give you a good idea of your odds before you throw that crucial Poké Ball!
function calculateCatchRate() {
var targetLevel = parseFloat(document.getElementById("targetLevel").value);
var pokemonLevel = parseFloat(document.getElementById("pokemonLevel").value); // Included for context, not directly in Gen 1 formula calculation
var baseCatchRate = parseFloat(document.getElementById("baseCatchRate").value);
var currentHP = parseFloat(document.getElementById("currentHP").value);
var maxHP = parseFloat(document.getElementById("maxHP").value);
var statusCondition = parseInt(document.getElementById("statusCondition").value);
var ballTypeMultiplier = parseFloat(document.getElementById("ballType").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Validate inputs
if (isNaN(targetLevel) || isNaN(baseCatchRate) || isNaN(currentHP) || isNaN(maxHP) || isNaN(statusCondition) || isNaN(ballTypeMultiplier)) {
resultDiv.innerHTML = "Please enter valid numbers for all inputs.";
return;
}
if (baseCatchRate 255) {
resultDiv.innerHTML = "Base Catch Rate must be between 0 and 255.";
return;
}
if (currentHP < 0 || maxHP maxHP) {
resultDiv.innerHTML = "Invalid HP values. Current HP must be non-negative and less than or equal to Max HP, and Max HP must be greater than 0.";
return;
}
// Gen 1 Catch Mechanics Calculation (Simplified representation)
// Stage 1: Calculate the critical factor 'A'
// This is a simplified representation as the actual Gen 1 formula involves multiple checks and values.
// The core idea is that lower HP, better balls, and status conditions increase the chance.
// A simplified approach to represent the factors:
var hpFactor = (maxHP * 3 – currentHP * 2) * baseCatchRate / (maxHP * 3);
// Status Modifier
var statusModifier = 1;
if (statusCondition === 1) { // Sleep/Freeze
statusModifier = 2;
} else if (statusCondition === 2) { // Poison/Burn/Paralysis
statusModifier = 1.5;
}
// Combine factors
// The actual Gen 1 formula is more complex involving specific thresholds for shakes.
// This calculation provides an estimated catch chance based on the factors.
var modifiedCatchRate = hpFactor * statusModifier * ballTypeMultiplier;
// The game checks if a random number (0-255) is less than a calculated value.
// The actual catch rate is a complex series of checks. This calculator aims to
// give a rough probability based on the inputs.
// A commonly cited formula approximation for the 'A' value that determines catch success:
var A = (3 * maxHP – 2 * currentHP) * baseCatchRate * ballTypeMultiplier / (3 * maxHP);
// Apply status modifier to A
if (statusCondition === 1) { // Sleep/Freeze
A = A * 2;
} else if (statusCondition === 2) { // Poison/Burn/Paralysis
A = A * 1.5;
}
// The game then checks how many times the ball shakes.
// A successful catch requires 4 shakes in Gen 1. This formula calculates the probability
// of getting those shakes.
// The probability of a single shake is A/255.
// The probability of catching is (A/255)^4, but this is a VERY simplified view.
// A more direct representation of the "effective" catch rate that the game checks against:
var effectiveCatchRate = (A > 255) ? 255 : A; // Cap at 255
// The probability of catching is not directly (effectiveCatchRate/255) in Gen 1,
// as it depends on shake counts. However, a higher 'effectiveCatchRate' means
// a higher chance of successful shakes.
// We can represent the chance as the effective catch rate relative to the maximum possible.
var estimatedCatchChance = (effectiveCatchRate / 255) * 100;
// Display the result
resultDiv.innerHTML = `
Estimated Catch Chance: ${estimatedCatchChance.toFixed(2)}%
Note: This is an estimation for Gen 1 mechanics. Actual catch success depends on random number generation and shake counts.
`;
}
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