> For the complete documentation index, see [llms.txt](https://docs.wheelx.fi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wheelx.fi/overview/features/gas-fee-estimation.md).

# Gas Fee Estimation

Every cost is estimated upfront and included in the quoted output — no hidden fees, no surprises after signing.

<figure><img src="/files/6yYfF7rs5NvankMXB0rB" alt=""><figcaption></figcaption></figure>

### What Users See

Before a user signs a transaction, WheelX shows a clear breakdown of the total cost impact. Instead of presenting a single opaque fee number, we break it into three transparent components:

| Component              | Description                                                | Example                   |
| ---------------------- | ---------------------------------------------------------- | ------------------------- |
| **Swap Impact**        | Price impact caused by moving through DEX liquidity        | -$0.02 (-0.68%)           |
| **Dst Gas Fee**        | Destination chain gas required to complete the transaction | **Free** (when sponsored) |
| **WheelX Fee**         | Platform service fee for using WheelX infrastructure       | -$0.06                    |
| **Total Price Impact** | Sum of all cost components                                 | **-$0.08**                |

**The output amount shown is already net of all fees.** The user receives exactly what the quote displays — no additional charges are deducted after confirmation.

### How It Works

#### 1. Real-time price and gas data

WheelX continuously pulls live data from every supported chain and liquidity source, including:

* DEX pool prices and depth (for price impact)
* Current gas prices on source and destination chains
* Bridge relay costs and relayer availability

#### 2. Multi-hop route simulation

For routes that include multiple steps (e.g., bridge + swap), the system simulates each step and calculates the cumulative cost impact. This includes:

* Price impact on each DEX leg
* Gas cost on the destination chain
* Any bridge or relay fees
* The WheelX platform fee

#### 3. Fee sponsorship layer

Where enabled, WheelX can sponsor the destination gas fee so the user sees **Dst Gas Fee: Free**. This is especially important for payments and onboarding flows where users may not hold the destination chain's native token.

***

### Fee Components Explained

#### Swap Impact

Swap impact occurs when the trade size is large relative to the liquidity available in the DEX pool. It is expressed as both a dollar amount and a percentage of the trade.

> **Example:** A -$0.02 impact on an $11.72 trade means the user receives 0.68% less than the mid-market price due to DEX slippage.

#### Dst Gas Fee

This is the gas required to execute the final transaction on the destination chain. Depending on configuration, it may be:

* **Paid by user** — Deducted from the output or required as native gas token
* **Sponsored** — Covered by the merchant, app, or WheelX fee system, shown as **Free** to the user

#### WheelX Fee

The platform service fee for routing, bridging, and executing the transaction through WheelX infrastructure. It is always shown in dollar terms and deducted from the output amount.

***

### Why It Matters

* **No surprises** — All costs are visible before signing. Users know exactly what they will receive.
* **No extra gas tokens needed** — Sponsored gas fees let users pay with any token from any chain.
* **Better UX for payments** — Merchants can absorb gas costs so customers only see a clean final amount.
* **Easy comparison** — Total price impact makes it simple to compare routes across different bridges or DEXs.
* **Budget-friendly** — Large transactions are easy to plan because the full cost is quoted upfront.

### From Fee Estimation to Gasless Payments

Gas fee estimation is the foundation for fully **gasless transactions**:

1. **Estimate** the destination gas fee accurately.
2. **Sponsor** that fee via the Fee Sponsorship system.
3. **Show users a clean quote** where the only visible cost is the platform fee and swap impact.

This is how WheelX enables users to pay from any chain with any token — even if they don't hold ETH, BNB, or other native gas tokens on the destination chain.


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