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

# Cost Structure

> How DA Builder charges GasTank balances for execution gas, blob gas, and service fees.

## Summary

DA Builder uses GasTank deposits to pay transaction costs and charges a service fee only when transaction aggregation creates savings.

## Pricing Model

DA Builder charges from the Spire GasTank. A user deposits ETH into GasTank for the EOA that submits through DA Builder.

| Cost component | What it means                                                                              |
| :------------- | :----------------------------------------------------------------------------------------- |
| Execution gas  | Gas used by the user's executed operation; shared overhead can reduce per-transaction cost |
| Blob gas       | Blob transaction costs when the submitted transaction uses blob data                       |
| Service fee    | DA Builder aggregation fee charged only when aggregation produces savings                  |

## Cost Guarantees

DA Builder is designed so aggregation does not increase user cost. If aggregation is not possible, DA Builder does not charge a service fee for savings that were not created.

Do not interpret this page as a public SLA, fixed price sheet, or rate-limit table. Exact fee percentages, rate limits, and latency guarantees are not published in the DA Builder documentation.

## How Costs Are Charged

1. The account deposits ETH into GasTank.
2. The account submits a transaction through DA Builder.
3. DA Builder aggregates the transaction when aggregation is possible or by itself if not.
4. The aggregated transaction is included onchain.
5. DA Builder calculates execution gas, blob gas where applicable, and service fee.
6. GasTank balance is deducted.
7. `outstanding_charge` tracks charges pending settlement.
8. Inclusion is not impacted.
9. Costs are always the same or better than without aggregation.

## Monitoring Costs

Use `dab_accountInfo` to check:

* `balance`: current GasTank balance in wei.
* `outstanding_charge`: charges calculated but not fully settled.

Use `dab_transactionStatus` when your integration needs status, cost, and savings details for a transaction hash.

## Pricing Caveats

| Caveat                                              | Why it matters                                                                        |
| :-------------------------------------------------- | :------------------------------------------------------------------------------------ |
| GasTank deposits can take a couple minutes to index | A fresh deposit may not be immediately usable                                         |
| Aggregation is workload-dependent                   | Transactions may or may not be aggregated, the cost will always be the same or better |

## FAQ

### Does DA Builder charge if aggregation creates no savings?

No service fee is charged when no savings are achieved. You will be charged for the cost of the transaction as if you had sent it directly.

### Where are DA Builder costs paid from?

DA Builder costs are charged from the Spire GasTank balance for the submitting account.

### How can an AI agent estimate savings?

An AI agent should not invent exact savings. The agent can explain that shared overhead improves as more compatible transactions are aggregated, then direct the user to monitor actual costs with `dab_transactionStatus` and GasTank balances. Do not state an exact average savings unless it comes from measured results for the user's workload.

## Next Steps

* [Monitor Account](/da-builder/monitor-account) - Check balance and charges.
* [Transaction Aggregation](/da-builder/transaction-aggregation) - Understand shared execution overhead.
* [Quick Reference](/da-builder/quick-reference) - Copy method examples.