Ethereum: Address Formats, Networks, and How to Swap ETH

Ethereum uses a single address format across dozens of different blockchains — which is exactly what makes it so easy to send ETH to the right address on the wrong network. Unlike Bitcoin's immediately visible address prefixes, every Ethereum-compatible address looks identical whether it's on mainnet, Arbitrum, Base, or Binance Smart Chain. That uniformity is convenient for wallets but causes permanent fund loss when users confuse which network their exchange or wallet expects.

The second thing that catches users off-guard: ETH is both an asset and a fee token. You need ETH in your wallet to send any ERC-20 token, USDT, or USDC on Ethereum mainnet. Run it down to zero and your wallet is effectively frozen for outgoing transactions, even if it holds thousands of dollars in other tokens.

By the end of this guide you'll understand ETH address formats, how to navigate network selection without guessing, how gas fees are structured, and how to safely swap and store ETH.

Ethereum Address Formats

Every Ethereum-compatible address is 42 characters: "0x" followed by 40 hexadecimal characters. There is no meaningful variation — no versions or format evolution like Bitcoin's legacy versus SegWit distinction.

The same address works across all EVM-compatible chains. Your mainnet ETH address also receives ETH on Arbitrum, Optimism, Base, Polygon, Binance Smart Chain, and any other EVM chain. This is both the convenience and the trap: an exchange expecting mainnet ETH will generate a deposit address that looks identical to their Arbitrum deposit address.

Ethereum addresses use EIP-55 checksumming: a mixed-case version (e.g. 0x742d35Cc6634C0532925a3b8D4C9cDe...) validates correctness without a separate checksum digit. Most wallets display and accept both mixed-case and all-lowercase versions. Always paste addresses from your wallet directly rather than typing them — a single wrong hex character routes funds to an address nobody controls.

Unlike Bitcoin, Ethereum has no concept of address rotation at the protocol level. Reusing the same receive address is safe and most wallets generate one address per account rather than cycling through new ones.

Network Selection: Mainnet, Layer 2s, and Other EVM Chains

Ethereum mainnet is the base settlement layer. Layer 2 networks — Arbitrum, Optimism, Base, zkSync, Scroll, and others — execute transactions separately and post data or proofs to Ethereum mainnet for finality. A third category, sidechains and alternative EVM chains like Polygon PoS, BNB Smart Chain, and Avalanche C-Chain, share the address format but have no direct security link to Ethereum.

When you receive ETH from a Zest swap, you're receiving native ETH on Ethereum mainnet. The coin selector shows the network label — always confirm it reads "Ethereum" and not "Arbitrum One," "BNB Smart Chain," or any other label before submitting your receiving address.

Network	Type	ETH version	Typical gas cost
Ethereum mainnet	L1	Native ETH	$0.05–$0.50 per transfer
Arbitrum One	L2 (optimistic rollup)	Bridged ETH	Under $0.01–$0.03
Optimism	L2 (optimistic rollup)	Bridged ETH	Under $0.01–$0.03
Base	L2 (optimistic rollup)	Bridged ETH	Under $0.01–$0.02
zkSync Era	L2 (ZK rollup)	Bridged ETH	Under $0.01–$0.03
Polygon PoS	Sidechain	Bridged ETH	Under $0.01
BNB Smart Chain	Alt chain	WETH (ERC-20)	$0.05–$0.50 in BNB

Sending ETH to the right address on the wrong network does not fail with an error. The transaction confirms. The funds arrive in a wallet you may or may not control on a network you didn't intend. Recovery requires having a wallet that uses the same seed phrase on both networks, which many do — but recovery still requires you to have access to that seed. Most ETH deposit failures trace back to this exact mismatch.

When a Zest swap asks for your receiving address, confirm two things before copying from your wallet:

1. Which chain your wallet is set to receive on
2. Which network the swap is sending on (shown in the coin selector)

If those match, proceed. If they differ, switch your wallet's active network before copying the address. For background on why bridging between these networks carries additional risk, the cross-chain bridge risks guide covers the attack surface in detail.

How Ethereum Gas Fees Work

ETH is the only currency that pays gas fees on Ethereum mainnet. Sending USDT, USDC, DAI, or any ERC-20 token still costs ETH — not the token you're sending. Users who hold only USDC on mainnet and no ETH cannot send anything until they acquire ETH for gas.

Ethereum adopted EIP-1559 with the London upgrade. Fees now have two components:

• Base fee: set by the protocol, burned rather than paid to validators. It adjusts up or down each block based on whether the previous block was above or below 50% capacity.
• Priority fee (tip): paid directly to the block proposer as an inclusion incentive. With most everyday activity now on Layer 2s, mainnet tips during quiet periods often sit well under 1 gwei. During real congestion — a token launch or a market shock — competitive tips can still climb to several gwei or more.

Total cost: (base fee + priority fee) × gas units. A standard ETH transfer uses 21,000 gas units. A token swap or DeFi contract interaction uses 80,000–400,000 gas units depending on the contract's complexity.

Gas prices fluctuate by time of day and market activity. Weekday business hours across North American and European time zones see the highest mainnet congestion. During market volatility — large price moves or major protocol launches — fees spike within seconds. For any fixed-rate swap, check current gas conditions before sending. A transaction with too low a fee can sit unconfirmed for the entire rate-lock window, causing the swap to expire with no output. Selecting the fast fee tier adds a buffer against sudden spikes.

Layer 2 networks still cost a fraction of mainnet, even now that mainnet gas itself has dropped, because they batch many transactions together and amortize the mainnet settlement cost — the gap widens sharply whenever mainnet activity spikes. If you're receiving ETH into an L2 wallet for DeFi use, those chains work with bridged ETH rather than native mainnet ETH — confirm the network label matches before sending.

Swapping Ethereum on Zest

Swapping ETH on Zest requires no account. Funds go directly to the wallet address you specify:

1. Select ETH as the source or destination coin. Check the network label in the coin selector — it should read "Ethereum." If sending ETH to Zest as the source, confirm your wallet is on Ethereum mainnet before signing the transaction.
2. Enter the amount. The widget shows the minimum and maximum limits for the current pair. Below-minimum amounts cannot be processed automatically.
3. Choose your rate type. Fixed locks in the exact output amount for the countdown window (typically 10–15 minutes), eliminating price risk during your transfer. Floating settles at market rate when your deposit confirms.
4. Enter the destination wallet address for the coin you're receiving. Compare at least the first four and last four characters to what your wallet displays — clipboard-hijacking malware replaces copied addresses with lookalikes that differ only in the middle characters.
5. Tap Exchange. You'll see a unique deposit address and the exact amount to send.
6. Send from your wallet using the fast fee tier. For fixed-rate swaps, send immediately after locking the rate.

The order page has a persistent URL — closing the tab doesn't cancel the swap. Ethereum typically requires 12–20 block confirmations before an exchange credits the deposit, putting the expected wait at 3–5 minutes under normal conditions. Floating rate removes the countdown pressure if you're uncertain about current gas conditions.

Storing Ethereum Safely

A hardware wallet is the baseline for any ETH amount you plan to hold. The private key stays in a signing device that never connects to the internet. Ledger and Trezor are the most widely used options compatible with Ethereum and all EVM chains. Any hardware wallet that signs EIP-1559 transactions supports modern ETH transfers and all ERC-20 tokens in the same account.

Your seed phrase — 12 or 24 words generated at wallet setup — recovers all Ethereum addresses across every EVM-compatible chain. The same seed phrase that recovers your mainnet ETH also recovers your Arbitrum, Base, and Optimism balances, because those accounts derive from the same private key.

Standard seed phrase practices:

• Write it on paper or engrave it on metal. Never photograph it, type it into any device, or store it in any digital system, including password managers and cloud storage.
• Keep copies at two separate physical locations to protect against fire, flood, or theft at any single site.
• Anyone who obtains the seed phrase has complete, permanent access to every account the seed generates across every EVM chain.

One Ethereum-specific point: if you hold liquid staking tokens like Lido's stETH or Rocket Pool's rETH, those are ERC-20 tokens in your same wallet. A hardware wallet that secures your ETH also secures staking positions. Just confirm which asset you're using when initiating a swap — stETH and rETH are distinct from native ETH and priced differently.

Before You Send: Five Checks

Run through this list before sending ETH to any address:

• Address is 42 characters starting with "0x" — no truncated, shortened, or pasted partial versions
• Network labels match: your wallet's active network is the same chain the recipient expects
• Enough ETH remains in your wallet to cover gas — sending any token still requires ETH for the fee
• First four and last four characters of the recipient address match what your wallet shows
• For fixed-rate swaps: fee tier is set to fast, and you're sending immediately after locking the rate

Those five checks account for the majority of failed, stuck, or lost ETH transactions.