None (1.0x)
Sleep or Freeze (2.0x)
Paralysis, Burn, or Poison (1.5x)
How the Pokémon Emerald Catch Formula Works
In Generation III (Pokémon Emerald, Ruby, and Sapphire), the catch rate calculation is a multi-step process. Unlike later games, it uses specific integer math that can make capturing Legendaries like Rayquaza or Kyogre quite difficult.
If 'a' is 255 or higher, the Pokémon is caught instantly. Otherwise, the game performs "shake checks."
Key Factors Influencing Success
HP: Reducing the Pokémon to 1 HP (using moves like False Swipe) significantly increases the catch value.
Status: Sleep and Freeze are the most effective status conditions, providing a 2x multiplier. Paralysis, Poison, and Burn provide 1.5x.
Ball Multipliers: Using an Ultra Ball doubles your chances compared to a standard Poké Ball. Specialty balls like the Net Ball can offer up to 3x multipliers in specific scenarios.
Common Catch Rates in Emerald
Pokémon Type
Base Rate
Example Pokémon
Common Pokémon
255
Magikarp, Zigzagoon, Wurmple
Starter Pokémon
45
Treecko, Torchic, Mudkip
Semi-Rare
30
Absol, Skarmory
Legendaries
3
Rayquaza, Kyogre, Groudon, Regice
Pro Strategy: The "False Swipe" Technique
To maximize your odds in Pokémon Emerald, always bring a Pokémon that knows False Swipe. This move is guaranteed to leave the target with at least 1 HP. Pair this with a Pokémon that can induce Sleep (like Breloom with Spore) to achieve the highest possible catch probability without using a Master Ball.
function calculateCatchRate() {
var maxHP = parseFloat(document.getElementById('maxHP').value);
var currentHP = parseFloat(document.getElementById('currentHP').value);
var baseRate = parseFloat(document.getElementById('baseRate').value);
var ballMod = parseFloat(document.getElementById('ballType').value);
var statusMod = parseFloat(document.getElementById('statusEffect').value);
var resultDiv = document.getElementById('poke-result');
if (isNaN(maxHP) || isNaN(currentHP) || isNaN(baseRate) || maxHP <= 0) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Please enter valid numerical values. Max HP must be greater than 0.';
return;
}
if (currentHP > maxHP) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Current HP cannot be higher than Max HP.';
return;
}
// Master Ball logic
if (ballMod >= 255) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Catch Probability: 100%The Master Ball never fails!';
return;
}
// Step 1: Calculate 'a'
// Formula: a = (((3 * Max HP – 2 * Current HP) * Rate * Ball) / (3 * Max HP)) * Status
var a = (((3 * maxHP – 2 * currentHP) * baseRate * ballMod) / (3 * maxHP)) * statusMod;
var probability = 0;
if (a >= 255) {
probability = 100;
} else {
// Step 2: Calculate 'b' for shake checks
// b = 65536 / (255/a)^0.25
var b = 65536 / Math.pow((255 / a), 0.25);
// Probability of success is (b/65536)^4
// In Gen 3, a shake check succeeds if a random number [0, 65535] is 100) probability = 100;
if (probability 0) ? Math.ceil(100 / probability) : "Infinite";
resultDiv.style.display = 'block';
resultDiv.innerHTML = '
Catch Results:
' +
'Catch Probability per Ball: ' + probability.toFixed(2) + '%' +
'Catch Value (a): ' + Math.floor(a) + ' / 255' +
'Estimated Balls Needed: ' + expectedBalls + " +
'Note: This uses the standard Gen III logic. Luck always plays a factor!';
}