The short answer
Each EVM network has a numeric chain ID — 1 for Ethereum, 137 for Polygon PoS, 8453 for Base, 42161 for Arbitrum One, 10 for OP Mainnet, 56 for BNB Smart Chain. Your wallet includes it when signing so the transaction cannot be replayed elsewhere. Verify a chain ID against an independent list before trusting a network someone has added for you.
Why the number exists
EVM networks share an address format and a transaction format. Without something distinguishing them, a transaction signed on one network could be rebroadcast on another and would be just as valid there — a replay. The chain ID is included in what you sign, so a signature is bound to one network.
This is why the same address can hold different balances on different chains without the transactions interfering. It is also why an interface that shows you the wrong network is dangerous: you may sign something correct for a network you did not intend.
Chain IDs for the networks in this guide
| Network | Chain ID | Gas asset |
|---|---|---|
| Ethereum | 1 | ETH |
| OP Mainnet | 10 | ETH |
| BNB Smart Chain | 56 (0x38) | BNB |
| Polygon PoS | 137 | POL |
| Base | 8453 | ETH |
| Arbitrum One | 42161 | ETH |
TRON and Solana are not EVM networks and do not use EVM chain IDs. They have their own identifiers and address formats, which is why an address from one will not paste into the other.
Verifying a network before you trust it
When a site offers to add a network to your wallet, it supplies the name, the chain ID, the RPC endpoint and the currency symbol. None of that is authenticated by your wallet. MetaMask’s own guidance is to check the details against an independent list such as Chainlist, and notes that a network absent from such a list is either very new or of questionable quality.
The standard behind this, EIP-3085, is equally direct about the underlying rule: a wallet should use only the submitted chain ID to sign transactions and never a chain ID received from an RPC endpoint, because a malicious or faulty endpoint could return an arbitrary value and cause you to sign for an unintended chain.
The practical version: the name in your network switcher is a label someone typed. The chain ID is the identity.
The RPC endpoint is part of the trust
Adding a network also points your wallet at an RPC endpoint, which is how it reads balances and broadcasts transactions. MetaMask warns that a malicious provider can lie about the state of the chain, withhold transactions, and record your activity and IP address.
A wrong balance or a transaction that never seems to broadcast can be a symptom of a bad endpoint rather than a problem with your funds. Prefer endpoints published by the network itself or by a provider you already rely on, and treat an endpoint supplied by an unfamiliar site as untrusted.
Frequently asked
What is the chain ID for Ethereum?
Ethereum mainnet is chain ID 1. Polygon PoS is 137, Base is 8453, Arbitrum One is 42161, OP Mainnet is 10 and BNB Smart Chain is 56.
Can two networks share a chain ID?
They are not supposed to, because that would defeat replay protection. A duplicate or unexpected chain ID is a strong reason to distrust the network details you were given.
Does the network name in my wallet matter?
Only as a label for you. The chain ID and the RPC endpoint determine what actually happens. A network named after a well-known chain can point anywhere.
Is it safe to add a network from a website prompt?
Only after you verify the chain ID and endpoint independently. Wallets do not authenticate what a site submits.
Before you act
- Check a chain ID against an independent list before trusting a new network.
- Treat the network name as a label, not as identification.
- Prefer RPC endpoints published by the network or a provider you already use.
- Confirm your wallet is on the intended network before signing.
Sources & further reading
- MetaMask: verifying custom network information
Checking chain ID and network details against an independent list.
- EIP-3085: wallet_addEthereumChain
Use only the submitted chain ID for signing, never one returned by an RPC endpoint.
- Polygon: network details
Polygon PoS mainnet chain ID 137.
- BNB Chain: JSON-RPC endpoints
BSC mainnet chain ID 0x38, 56 in decimal.
Sources checked on 18 September 2026. Network features and platform support can change; check the relevant provider before acting.
AI-assisted editorial content; no independent expert review or transaction verification is claimed. Tokens and bridges carry issuer, market and smart-contract risks. This is educational information, not investment advice. Read our editorial policy.