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

# Gas fees and transaction lifecycle

> How gas estimation, fee payment, and transaction confirmation work on Autheo Chain.

Autheo Chain uses the same gas model as Ethereum, with fees denominated in `aauth` (the base unit of THEO). This page explains how to estimate gas, set fees, and understand when a transaction is finalized.

## Fee denomination

All transaction fees are paid in `aauth`:

| Unit                 | Conversion                          |
| -------------------- | ----------------------------------- |
| `1 aauth`            | Smallest fee unit                   |
| `1 THEO`             | 10¹⁸ `aauth`                        |
| Typical transfer fee | \~5,000,000 `aauth` (0.000005 THEO) |

## Gas estimation

Use `--gas auto` with `--gas-adjustment 1.5` for CLI transactions to avoid out-of-gas failures:

```bash theme={null}
autheod tx bank send mykey <recipient> 1000000000000000000aauth \
  --chain-id autheo_2127-1 \
  --keyring-backend file \
  --gas auto \
  --gas-adjustment 1.5 \
  --fees 5000000aauth
```

For EVM transactions, use `eth_estimateGas`:

```bash theme={null}
curl -X POST https://rpc1.autheo.com \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_estimateGas",
    "params": [{"from": "0x...", "to": "0x...", "value": "0xDE0B6B3A7640000"}],
    "id": 1
  }'
```

## Gas price

Query the current suggested gas price:

```bash theme={null}
curl -X POST https://rpc1.autheo.com \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_gasPrice","params":[],"id":1}'
```

In ethers.js:

```javascript theme={null}
const feeData = await provider.getFeeData();
console.log("Gas price:", feeData.gasPrice.toString(), "aauth");
```

## Transaction lifecycle

```
1. Submit → mempool
2. Validator includes tx in next block (~5 seconds)
3. Block committed (1 confirmation = finalized in CometBFT)
4. Receipt available via eth_getTransactionReceipt
```

Autheo Chain uses CometBFT BFT consensus — **one block confirmation is final**. There are no reorgs. You do not need to wait for multiple confirmations as you would on Ethereum.

## Checking transaction status

**CLI:**

```bash theme={null}
autheod query tx <txhash> --chain-id autheo_2127-1
```

**JSON-RPC:**

```bash theme={null}
curl -X POST https://rpc1.autheo.com \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_getTransactionReceipt","params":["0x<txhash>"],"id":1}'
```

A receipt with `"status": "0x1"` means success. `"status": "0x0"` means the transaction was included but reverted.

## Common fee errors

| Error                           | Cause                  | Fix                                                   |
| ------------------------------- | ---------------------- | ----------------------------------------------------- |
| `insufficient funds for gas`    | Wallet balance too low | Fund the account with more `aauth`                    |
| `out of gas`                    | Gas limit set too low  | Use `--gas auto --gas-adjustment 1.5`                 |
| `tx already in mempool`         | Duplicate transaction  | Wait for existing tx to confirm or increase gas price |
| `signature verification failed` | Wrong chain ID         | Pass `--chain-id autheo_2127-1`                       |

## EIP-1559 support

Autheo Chain supports EIP-1559 fee transactions (type 2). Use `maxFeePerGas` and `maxPriorityFeePerGas` in ethers.js:

```javascript theme={null}
const tx = await wallet.sendTransaction({
  to: recipient,
  value: ethers.parseEther("1.0"),
  maxFeePerGas: ethers.parseUnits("25", "gwei"),
  maxPriorityFeePerGas: ethers.parseUnits("1", "gwei")
});
await tx.wait(1); // 1 confirmation is final
```