# Gacha Probability Calculator

URL: https://tools.otaku-dojo.com/en/gacha-probability-calculator
Updated: 2026-10-04

The Gacha Probability Calculator computes the exact probability of getting at least K featured units within N pulls, the average number of pulls needed and how many pulls give you 50%, 90% or 99% odds. It models base rate, soft pity ramps, hard pity and the 50/50 rule (lose once and the next one is guaranteed). Presets cover common 90-pull character banners and 80-pull weapon / light cone banners, or enter any game's rates.

## How to use the Gacha Probability Calculator

1. Pick a probability model preset, or choose "Custom" and enter the rates and pity rules.
2. Enter how many pulls you plan to do and how many copies you want (e.g. 1, or 7 for max constellations / eidolons).
3. If you already have pity built up or a guarantee, enter "Current pity" and tick "Guaranteed".
4. Your success chance, average pulls and pulls needed appear instantly; add a cost per pull to convert to currency.

## Specs & key facts

- **Method**: Exact dynamic programming (not Monte Carlo)
- **Rules**: Base rate, soft pity ramp, hard pity, featured rate, guarantee after losing
- **Presets**: 90-pull character banner (0.6%, +6%/pull from 74, 50/50); 80-pull weapon / light cone banner (0.8%, +7%/pull from 66, 75/25)
- **Output**: Chance within N pulls, average pulls, pulls for 50 / 90 / 99%, worst case, cumulative chart
- **Copies**: 1 to 7
- **Data note**: Soft pity values come from community statistics; official announcements take precedence

## Examples: 90-pull character banner: chance to get the featured unit in 90 pulls

```text
Model: 90-pull character banner | 90 pulls | 1 copy | 0 pity, no guarantee
```

→

```text
Chance: 59.4%
Average: 93.5 pulls
50% odds: 80 pulls | 90% odds: 155 pulls
Worst case: 180 pulls
```

## Examples: A 1% rate with no pity — will 100 pulls hit?

```text
Rate 1% | no pity | 100 pulls
```

→

```text
Chance of at least one: 63.4%
Average: 100 pulls
```

## FAQ

### With a 1% rate, are 100 pulls guaranteed to hit?

No. With independent pulls, the chance of at least one hit in 100 pulls is 1 − 0.99¹⁰⁰ ≈ 63.4%, so about 36.6% of players get nothing. You need about 459 pulls for 99% odds.

### Why is the "consolidated rate" 1.6% when the base rate is 0.6%?

The consolidated rate includes pity: on average a top-rarity drop takes about 62 pulls, which is roughly 1.6% per pull. This calculator uses the base rate plus pity rules and matches that figure.

### I already have 60 pity. How do I account for it?

Enter 60 in "Current pity". Existing pity brings hard pity closer and reduces the pulls you need; if you lost your last 50/50, also tick "Guaranteed".

### Which games does it work for?

Any gacha with independent pull rates plus pity — just enter the game's published rates. Presets fit 90-pull character banners with 50/50 and 80-pull weapon / light cone banners with 75/25.

### What is the difference between "average pulls" and "50% odds"?

The average is pulled up by very unlucky cases; 50% odds is the point by which half of players succeed. When saving currency, plan for the 90% figure.