---
name: avax-gas
description: Estimate Avalanche transaction fees using the target network and current execution rules instead of fixed cost claims.
---

# Gas & transaction costs

Source review: 2026-09-06. Recheck network-dependent facts before use.

1. Confirm the target with [Networks](../networks/SKILL.md) and check [Upgrades](../upgrades/SKILL.md). Read current fee data from that network; do not carry a historic 25 nAVAX floor, a testnet rule or an Ethereum fee assumption into mainnet.
2. Simulate the exact sender, destination, calldata and value. Estimate gas through the target RPC and choose bounded fee caps using the provider's supported fee methods. Report estimation failure instead of substituting an arbitrary successful estimate.
3. Calculate a preflight maximum from gas limit × maximum fee per gas; distinguish it from expected cost. Reserve native AVAX for C-Chain execution even when the transferred token is USDC or WAVAX. A custom L1 can use a different gas asset.
4. After execution read the receipt and reconcile the charged gas and effective gas price against the applicable network rules. Report actual cost in native units; add fiat only with a timestamped price source.
5. Test gas-limit behavior against the target upgrade. The reviewed Helicon rule charges `max(gasUsed, gasLimit / 2)` on activated networks; blindly multiplying an estimate by a huge safety margin can increase the fee. Refresh the applicable rule from the linked release and fee documentation.

**Evidence to return:** network, observation time/block, simulation result, gas estimate, maximum budget and, if broadcast was authorized, realized receipt cost.

## Primary sources

- [Avalanche transaction fees](https://build.avax.network/docs/rpcs/other/guides/txn-fees)
- [Helicon activation and behavior](https://build.avax.network/docs/primary-network/helicon-upgrade)

## Reproduce a pinned fee probe

From the executable bundle root run `node examples/network/inspect.mjs`. It performs raw chain validation, block-pinned eth_estimateGas for WAVAX balanceOf, and eth_feeHistory checked against the same block base fee. Evidence lives at `research/parity-network/live-evidence.json`.

The base-fee-only cost of that view call is illustrative: it excludes priority fees and is not a swap, proof or future transaction cost. For a real operation estimate exact sender/calldata/value and account state; preserve failures instead of inventing a successful gas limit. Include approval reset, approval and final operation in the budget.

Gas is execution units, fee price is native smallest units per gas, and transferred token amount is separate. Maximum fee budget is not necessarily expected cost. Native sufficiency includes transfer value plus fees, even when the app mostly displays USDC. Record receipt-derived realized charges only for the network actually executed.

Recheck [Upgrades](../upgrades/SKILL.md) before applying Helicon charge rules. A rule active on Fuji is not a mainnet rule when activation remains unscheduled, and an Anvil receipt is not a public C-Chain fee observation.