# Gas Costs on L2s

The gas costs on L2s can be split into two parts.

* **L2 Execution Costs**: which describes the L2 execution-related gas costs.
* **L1 Data Fee Costs**: which describes costs associated with posting L2 calldata on the associated L1.
* **Cost Comparison to Groth16 Verification w/o UPA**

We also provide `gwei` numbers for Base at the time of writing this article. A summary of the results is shown in the table below.

| Batch Size | gwei cost w/ UPA on Base | gwei Cost w/o UPA on Base |
| ---------- | ------------------------ | ------------------------- |
| 32         | 3000                     | 11,560                    |
| 64         | 1160                     | 11,560                    |

## L2 Execution Costs

The L2 execution gas of `verifyMixedAggregatedProof` is about the same as the L1 execution cost for this transaction. For a batch size of 32, this is about [775,000](https://sepolia.etherscan.io/tx/0x2b387f0b4970735bd8c6117389ba7b49b46e425c192b85be05cde016c7354756).

### L2 gas for querying if a proof/submission is verified

This cost is the same as in the[ L1 case ](/developer-guide/gas-costs-on-l1s.md)and comes out to **22,000.**

### Total per-proof L2 gas

For batch size 32, the total per-proof **L2 gas**, comes out to:

775,000 / 32 + 22,000 = 24,000 + 22,000 = **46,000 gas**

### `gwei` cost

At the time of writing this doc, [Base gas price](https://tokentool.bitbond.com/gas-price/base) was 0.036 gwei, so the total per-proof gwei cost is 46,000\*0.036 = **1650 gwei** for a batch size of 32.

## L1 data fee

To get the exact L1 cost in `gwei` we need to compute the `l1_data_fee`, as explained in this [document](https://docs.optimism.io/stack/transactions/fees).

`l1_data_fee = tx_compressed_size * weighted_gas_price`

The `weighted_gas_price` is independent of the particular transaction. This number is also chain-specific. It is a bit difficult to get exact number but backtracking of BaseScan it seems to be in the 10 `gwei` range.

The `tx_compressed_size` is th enumber of non-zero bytes in the calldata which is about 4300 bytes for a `verifyMixedAggregated` proof [transaction](https://sepolia.etherscan.io/tx/0x2b387f0b4970735bd8c6117389ba7b49b46e425c192b85be05cde016c7354756). So the L1 data fee comes out to about 43,000 `gwei` for the entire transaction or **1350** `gwei` per-proof.

## **Cost Comparison to Groth16 Verification w/o UPA**

* L2 execution cost is about **250,000 gas**. Converting to `gwei` gas prices on Base Chain at the time of writing this docs gives 250,000 \* 0.036 = **9000** `gwei`.
* Groth16 proof consists of 256 bytes of calldata so the `l1_data_fee` for Base Chain is 256 \* 10 = **2560** `gwei`.

So totally the cost is **11,560** `gwei` per-proof, as compared to **1650 + 1350 = 3000** `gwei` per-proof when using UPA. This is about a 4x savings of **7560** `gwei.`


---

# Agent Instructions: Querying This Documentation

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

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.nebra.one/developer-guide/gas-costs-on-l2s.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.