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

# bonding curve

Every RobinFun token trades on a **constant-product bonding curve** with virtual reserves — the same battle-tested model behind the most widely used launchpads.

## How pricing works

A constant-product curve keeps the product of two reserves constant:

```
x * y = k
```

| Term | Meaning                                                          |
| ---- | ---------------------------------------------------------------- |
| `x`  | The ETH reserve — part virtual, part real ETH paid in by buyers. |
| `y`  | The token reserve remaining on the curve.                        |
| `k`  | A constant, fixed at creation.                                   |

Because the product is fixed, buying tokens (removing `y`) requires adding ETH (`x`), which pushes the price up. Selling does the reverse. The **virtual reserve** sets the starting price and smooths the early curve, so the very first buys aren't disproportionately cheap.

## USD-denominated targets

RobinFun denominates its parameters in **USD** and snapshots them to ETH at the moment a token is created:

* The starting market cap ($4,000) and the graduation raise ($9,300) are expressed in USD.
* At creation, those USD figures are converted to ETH using a price snapshot, and the curve is fixed from that point on.
* The curve then runs purely in ETH — later moves in the ETH price don't shift a live token's targets.

This gives creators consistent, predictable economics regardless of the ETH price on launch day.

{% hint style="info" %}
Because of the snapshot, the exact amount of ETH a token needs to graduate depends on the ETH price at the moment it was created.
{% endhint %}

## Key properties

* **Deterministic** — the price is a pure function of how much has been bought. No order book, no market maker.
* **Symmetric** — the same curve governs buys and sells. You can sell back into the curve at the current price at any time until the curve fills; once the raise target is hit, trading pauses briefly until the permissionless [graduation](broken://pages/ee729c7a4bd3fdbfa657e55e06a9a6b9dd6c4959) executes.
* **Backed by real ETH** — the ETH paid in by buyers stays in the curve as backing while it's live, so sellers can always exit.

## What "real ETH" means

As people buy, real ETH accumulates in the curve (`realEth`). That ETH is the backing for everyone holding the token — it's what lets holders sell back. It is **reserved and protected**: the factory accounts for each token's ETH independently, and — aside from the 1% trade fee taken on each buy and sell (see [Fees](broken://pages/4507dfe7eef9af897ddbef4be256c4a624431389)) — curve ETH can only ever leave by being returned to sellers or by moving into the Uniswap pool (and treasury share) at [graduation](broken://pages/ee729c7a4bd3fdbfa657e55e06a9a6b9dd6c4959). It is not withdrawable by the team.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://robinfun.gitbook.io/robinfun-docs/bonding-curve.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.