Gacha Pull Simulator
Simulate single or 10× pulls with a configurable rate, soft pity and hard pity.
Overview
The Gacha Pull Simulator models the loot-box mechanics used in mobile games like Genshin Impact, Honkai: Star Rail, Fate/Grand Order, and many others. You set the base rate, soft-pity threshold, hard-pity guarantee, and pull batch size; the simulator runs single or 10x pulls and tracks pity progress, total currency spent, and the count of high-rarity drops you've earned.
It's useful for testing whether a budget will likely reach a target character before the banner ends, for understanding why your "guaranteed 5-star within 90 pulls" sometimes feels expensive, and for visualising the shape of pity systems without spending real money.
How it works
Each pull samples uniformly from [0, 1] and compares against the effective rate. The effective rate starts at the base value (commonly 0.6 percent for top rarity), holds constant up to the soft-pity threshold, then ramps linearly until it reaches near-certain hit at the hard-pity threshold. After any successful pull, pity counters reset to zero and the next pull starts the ramp again.
Soft pity smoothes out the pull distribution: rather than every pull having the same low chance, the chance climbs sharply toward the hard cap. The combined effect produces a near-bell-shaped distribution of "pulls per drop", with a long tail truncated by hard pity. Many games layer a 50/50 mechanic on top — even when a top-rarity drop fires, there's a chance it's an off-banner unit — which the simulator can toggle on.
Examples
- Base 0.6 percent, soft pity at pull 74, hard pity at 90: average pulls per 5-star is roughly 62.
- A 10x batch shows the typical experience — most batches return zero 5-stars, occasional batches return one, and within hard-pity range nearly every batch returns one.
- Saving 90 wishes guarantees one 5-star, but with the 50/50 off-banner rule, getting your target 5-star is only 50 percent likely on that hit.
- Targeting a specific character with 50/50 protection typically takes 180 wishes worst-case (one off-banner + one guaranteed banner unit).
FAQ
Are the simulator's rates realistic?
The defaults match Genshin Impact's published rates. Other games tweak the curve; configure the inputs to match yours.
What is soft pity?
A gradually rising drop chance that kicks in after a fixed number of unsuccessful pulls, making top-rarity drops near-certain by the hard pity threshold.
Does the simulator use real currency?
No — it's a math model. No microtransactions are made.
Why does pity feel longer than the average?
Because the distribution has a long tail in the early pulls; the median is shorter than the worst-case but the few unlucky players who hit hard pity remember it vividly.
Can I export pull histories?
Each simulation logs the per-pull result, which you can copy into a spreadsheet for further analysis.