Gacha Expected Value Calculator
Estimate pull cost, pity odds and success rates before you spend
你想算什麼?
下面已用原神預設算好,改幾個數字就好
進階設定(可選)
想自己調機率、保底、進度的話再展開
遊戲預設
看懂這些數字(機制白話說明)
0.6% 是基礎出五星機率;74 抽起進入「軟保底」機率快速上升,90 抽是「硬保底」一定出;50/50 指第一隻五星有一半機率不是當期 UP 角色(歪了),歪了之後下一隻五星 100% 是 UP。
機率設定
進度追蹤
反向計算
我有多少抽,成功率是多少?
計算結果
想穩出,建議抓 90% 這檔
累計機率曲線
模擬抽卡
常見情境,一鍵快算
What is gacha expected value?
Gacha expected value is the long-run average number of pulls needed for a target item. Based on geometric distribution theory, without pity the expected pulls are roughly 1 divided by the drop rate — for example, a 0.6% character has an expected value of about 167 pulls. Pity, soft pity and guarantee mechanics can reduce that average significantly, but they do not remove randomness.
Pity Mechanics Explained
Pity mechanics come in two forms: "hard pity" and "soft pity." Hard pity guarantees a high-rarity result once you reach a fixed number of pulls. Soft pity means that starting from a certain pull count, the probability rises with every pull. In Genshin Impact, for example, soft pity begins at pull 74 and hard pity guarantees a 5-star at pull 90.
Soft Pity Mechanics
Soft pity means that from a certain pull count onward, the odds for each pull climb sharply. Using Genshin Impact as an example: pulls 1-73 sit at the base rate of 0.6%, then starting at pull 74 the rate increases by roughly 6% per pull until it reaches 100% at pull 90. Community statistics show that about 80% of 5-star results land between pulls 74 and 80.
50/50 System Explained
The 50/50 system means that the first time you pull a 5-star, there is a 50% chance it's the current featured (rate-up) character and a 50% chance it's a standard/off-banner 5-star (commonly called "losing the 50/50"). If you don't get the featured character, your next 5-star is 100% guaranteed to be the featured one — commonly called the "big pity" or hard guarantee.
Formula Notes
- Simple mode: expected pulls = 1 ÷ drop rate.
- Advanced mode: expected pulls = (1 - (1-p)^G) ÷ p, where G = hard pity count.
- Professional mode: accounting for soft pity + 50/50, expected pulls ≈ 62.5 × 1.5 = 93.75 pulls.
Frequently Asked Questions
Why does my luck feel worse than the calculator?
Each pull is an independent random event — past results do not affect future ones. Even after many pulls without a hit, the odds on your next pull remain the same. This is a common misunderstanding known as the "gambler's fallacy." Short-term results can be far above or below the average; the calculator describes probability over many attempts, not a promise for your next pull.
Does soft pity matter?
Yes. According to community statistics, about 80% of Genshin Impact 5-stars appear between pulls 74 and 80, so soft pity has a significant effect — it lowers the expected pull count from roughly 167 pulls down to about 62.5 pulls.
Is the hard pity (guarantee) really 100%?
Yes. When your previous 5-star was not the featured character (you "lost" the 50/50), your next 5-star is 100% guaranteed to be the current featured character — this is the hard guarantee, also called "big pity."
How different are the odds across games?
The difference is significant. FGO has no pity system at all. Arknights has soft pity but no hard pity. Genshin Impact and Honkai: Star Rail both have a full system combining soft pity, hard pity, and the 50/50 mechanic.
Related Calculators
For other chance and planning tools, try the random wheel selector or the percentage calculator.
Disclaimer
This calculator is for reference only and does not constitute spending advice. Gacha pulls are random events — please spend responsibly and play in moderation. All probability figures should be verified against each game's official announcements.