Definition

Gas fees are the costs you pay to the blockchain network in order to have your transaction included in a block. On Ethereum and all EVM-compatible chains (Polygon, Arbitrum, Optimism, etc.), every on-chain operation — a token transfer, a contract interaction, a bridge deposit — consumes a unit called gas, and you pay for that gas in the chain's native token.

On Ethereum mainnet, gas is paid in ETH. On Polygon, it is paid in MATIC. On Avalanche C-Chain, it is paid in AVAX.

How Gas Fees Are Calculated

Gas fees have two components:

Gas units — how much computational work a transaction requires. A simple ETH transfer uses 21,000 gas. A complex DeFi interaction can use hundreds of thousands of gas.
Gas price — what you are willing to pay per unit of gas. On Ethereum post-EIP-1559, this is broken into:
- Base fee — set by the network, burned (not paid to validators)
- Priority fee (tip) — paid directly to the validator to incentivize inclusion

Total cost = Gas units × (Base fee + Priority fee)

Gas Fees in Wallet Migration

When migrating a wallet with many assets, gas fees are a meaningful planning consideration:

Each transaction costs gas — a migration with 15 token transfers costs gas 15 times
Native token must remain for gas — you cannot transfer all of your ETH before paying gas on remaining transfers. The migration planner accounts for this.
Cross-chain bridge deposits cost mainnet gas (often the most expensive step)
Bridge withdrawals on L2s are typically cheap (Arbitrum, Optimism) or near-free (Polygon)

L2 Gas Savings

L2 chains like Arbitrum and Optimism process transactions off-chain and post batches to Ethereum. This dramatically reduces per-transaction gas costs:

Ethereum mainnet: $5–$50+ per complex transaction during congestion
Arbitrum/Optimism: typically $0.05–$0.50 for the same operation
Polygon PoS: typically under $0.01

This is one of the most common reasons users migrate assets from Ethereum mainnet to an L2.

Gas Estimation in MovingWallet

MovingWallet estimates gas for every step of a migration plan before you sign. Estimates are based on current network conditions and simulated transaction traces. Because gas prices fluctuate, actual costs may differ slightly from estimates — but the simulation ensures you are not caught off-guard by unexpected failures.