In Path of Exile, the items that drop from enemies are determined by a complex interaction of various modifiers. This calculator focuses on Increased Item Quantity (IIQ), which governs the total number of items dropped, rather than Increased Item Rarity (IIR), which affects the "tier" (Magic, Rare, Unique) of the items that have already been rolled to drop.
The Core Formula
While the exact internal code is proprietary to Grinding Gear Games, the community-accepted formula for calculating drop multipliers is generally multiplicative between different sources:
Effective Drop Rate = Base Chance × Player IIQ Multiplier × Map IIQ Multiplier × Party Multiplier
Note: Player IIQ is subject to diminishing returns when it comes to high values, though Map IIQ and Party bonuses are currently considered fully effective.
Key Terms for Farming
Player IIQ: Found on equipment like 'Goldwyrm' or 'Ventor's Gamble'. This is the most sought-after stat for Magic Find (MF) builds.
Map Quantity: This is the percentage shown at the top right of your map overlay. It is increased by rolling maps with Orbs of Alchemy, using Chisels, and adding Scarabs or Sacrificial Fragments.
Party Bonus: For every additional player in your party near the kill, you receive a multiplicative 50% increase to item quantity and a 125% increase to item rarity.
Example Calculation
If an Apothecary card has a base drop chance of 0.001% and you are running a map with 100% Quantity, using a character with 50% IIQ in a 2-man party:
Base: 0.001
Map Multiplier: 2.0 (100% increase)
Player Multiplier: 1.5 (50% increase)
Party Multiplier: 1.5 (2 players)
Total Chance: 0.001 * 2.0 * 1.5 * 1.5 = 0.0045%
function calculatePoeDrops() {
var baseChance = parseFloat(document.getElementById('baseChance').value);
var playerIIQ = parseFloat(document.getElementById('playerIIQ').value);
var mapIIQ = parseFloat(document.getElementById('mapIIQ').value);
var partySize = parseInt(document.getElementById('partySize').value);
if (isNaN(baseChance) || isNaN(playerIIQ) || isNaN(mapIIQ)) {
alert("Please enter valid numerical values.");
return;
}
// Conver percentages to multipliers
// 100% increase = 2.0 multiplier
var playerMult = 1 + (playerIIQ / 100);
var mapMult = 1 + (mapIIQ / 100);
// Party Multiplier: 50% quant per additional player
var partyMult = 1 + ((partySize – 1) * 0.5);
// Total Multiplier
var totalMult = playerMult * mapMult * partyMult;
// Final Drop Rate
var finalRate = baseChance * totalMult;
// Display
var resultBox = document.getElementById('poe-result-box');
var finalRateDiv = document.getElementById('finalRate');
var multiplierInfoDiv = document.getElementById('multiplierInfo');
resultBox.style.display = 'block';
finalRateDiv.innerHTML = "Effective Drop Rate: " + finalRate.toFixed(6) + "%" +
"Approx 1 in every " + Math.round(100/finalRate).toLocaleString() + " kills";
multiplierInfoDiv.innerHTML = "Your current setup provides a " + totalMult.toFixed(2) + "x total drop multiplier compared to a default white map.";
}