Game Win Rate & RNG Calculator

What this calculator does

This calculator answers two questions every competitive and gacha gamer asks. First: how many matches do I need to win in a row to push my win rate to a target number? Second: if an item has a fixed drop rate, what is the real chance I get at least one copy in a given number of pulls?

Both answers are computed with exact formulas, not estimates. The win streak result solves (wins + x) / (games + x) = target, and the gacha result uses the standard probability rule P = 1 - (1 - p)^n, the same math behind pity systems in Genshin Impact, Mobile Legends events, and most loot boxes.

How to use this calculator

1. For win rate: enter your current total matches, total wins, and the win rate you want to reach, then press Calculate win streak.
2. The result shows the exact number of consecutive wins required, with the math spelled out so you can verify it.
3. For gacha: enter the drop rate per pull as a percentage and how many pulls you plan to do, then press Calculate probability.
4. The result shows the chance of getting at least one drop, the expected pulls per drop, and the pulls needed for a 50%, 90%, and 99% chance.

Tips for reading the numbers

• A target win rate above your current one always needs a clean streak; one loss changes the math, so re-run the calculator after every session.
• Expected pulls (1 divided by the drop rate) is an average, not a guarantee. Roughly half of all players will need more pulls than the 50% mark.
• If your game has a hard pity (a guaranteed drop at a fixed pull count), treat our number as the luck-only baseline; hard pity caps the worst case.

Frequently Asked Questions