> For the complete documentation index, see [llms.txt](https://gacha-pull.gitbook.io/gacha-pull-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gacha-pull.gitbook.io/gacha-pull-docs/odds-and-platform-buyback.md).

# Odds & Platform Buyback

#### Odds

Odds determine what type of cards can be purchased and are displayed under each pack. Odds for each card type in packs are updated in real-time. 

<figure><img src="https://3832784580-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeD9ccjyPr9h5u4pfSviY%2Fuploads%2FJgOEqBlLAYBiuIWB6Rfv%2Fimage.png?alt=media&amp;token=b7a4d375-8990-4c94-bb3b-d5cb2e92f6cd" alt=""><figcaption></figcaption></figure>

#### Expected Value

Every pack on Gacha Pull contains a predefined distribution of items.\
The **Expected Value (EV)** of a pack is calculated as:&#x20;

```
EV = Σ (Value of item i × Probability of getting item i)
```

EV represents the *average value* you would receive if you opened a very large number of packs. *However, individual packs can be above or below expected value.* <br>

Each pack tier is designed with a **different EV and buyback %**, depending on its intended experience.

👉 This means higher-priced packs are generally more **capital-efficient**, while lower-priced packs are more **experience-driven**.

#### Market Value

Market value shown of each card is the median value of last-sold cards across various marketplaces. Our systems track reputable sources like eBay, alt.xyz and pricecharting.com, and then update market prices on a daily basis. This ensures we are showing the latest changes and best prices for our users.

#### Platform Buyback

If a user chooses to sell cards back to the platform, we offer **85% - 95% of fair market value** base on the pack type.&#x20;