> ## Documentation Index
> Fetch the complete documentation index at: https://docs.binibit.com/llms.txt
> Use this file to discover all available pages before exploring further.

# USBI Bridge (Bridge A)

> Convert Crystals (CRS) to USBI at 10,000 : 1, gated at Level 5.

**Bridge A** converts off-chain Crystals (CRS) into on-chain USBI on BiniChain.

## Conversion rate

```
10,000 CRS  =  1 USBI
```

Fixed rate. No oracle, no slippage, no fee on the bridge itself.

## Level gate

Bridge A unlocks at **Level 5** (50,000,000 XP). Below Level 5, users earn USBI entitlement but cannot bridge it on-chain.

This gate exists to ensure users have engaged with the app before flowing into BaiDEX, reducing thin-account spam.

## How it interacts with USBI entitlement

The bridge consumes:

* The user's [USBI entitlement headroom](/tokenomics/usbi-formula)
* The CRS being burned

Bridging does **not** create new USBI entitlement on its own — but the CRS spent during the bridge **does** count as XP, which raises your entitlement. So bridging is itself slightly self-funding.

Walk-through:

1. User has 10,000,000 CRS spent on lessons → 10,000,000 XP → 1,000 USBI entitlement
2. User wants to bridge 5,000,000 CRS into 500 USBI
3. Bridge action burns 5,000,000 CRS, mints 500 USBI on BiniChain
4. CRS spent during bridge counts as XP → total XP becomes 15,000,000 → entitlement becomes 1,500 USBI
5. User now has 500 USBI on-chain and 1,000 USBI of remaining entitlement

## Cap

USBI bridged on-chain is bounded by total USBI entitlement (welcome grant + XP-derived). A user cannot bridge more USBI than they are entitled to.

## Gas

The user pays BiniChain gas in **BINI** to execute the bridge transaction. See [BINI Bridge](/tokenomics/bini-bridge) for getting BINI native if needed.

## Sandbox vs Mainnet

USBI is a sandbox stablecoin — it is not externally redeemable. Bridge A operates inside the sandbox/testnet phase.

The mainnet evolution of USBI (or its replacement) is on the roadmap. See [BINI Token / Roadmap](/bini-token/overview).

## Formula in code

```javascript theme={null}
const RATIO = 10_000;

function usbiFromCrs(crsBurned) {
  return Math.floor(crsBurned / RATIO);
}

function crsRequiredFor(usbiTarget) {
  return usbiTarget * RATIO;
}
```

## Related

<CardGroup cols={2}>
  <Card title="USBI Formula" icon="function" href="/tokenomics/usbi-formula">
    The entitlement headroom
  </Card>

  <Card title="BINI Bridge" icon="bridge" href="/tokenomics/bini-bridge">
    Bridge B: BINI off → BINI native
  </Card>

  <Card title="Bini App / USBI Bridge" icon="mobile" href="/bini-app/overview">
    User-facing bridge UI
  </Card>

  <Card title="BaiDEX Pools" icon="layer-group" href="/baidex/overview">
    Where USBI provides liquidity
  </Card>
</CardGroup>