The Ethereum address format and why it matters when using MetaMask
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When you create a MetaMask account, or add a new account to your wallet, you're given a unique public address which you can find in the top-middle of your homepage.
On Ethereum and other networks compatible with the Ethereum Virtual Machine (EVM), public addresses all share the same format: they begin with 0x, and are followed by 40 alphanumeric characters (numerals and letters), adding up to 42 characters in total. They're also not case sensitive.
This address is a number, even though it also includes alphabetical characters. This is because the hexadecimal (base 16) system used to generate the address doesn't just use numerals, like our ten-digit decimal system. Instead, the hexadecimal system uses the numerals 0-9 and the letters A-F. This means it has 16 characters at its disposal, hence the name base 16. In computer science and many programming languages, the 0x prefix is used at the start of all hex numbers, as they are known, to differentiate them from decimal values.
How does this affect your daily use of MetaMask?
Interoperability: use the same address on different networks
As mentioned above, EVM-compatible networks all share the Ethereum address format. This is because they're generally 'hard forks', based heavily on Ethereum's design, or share key fundamentals. Not all are derived directly from Ethereum, though — many were developed separately and designed for compatibility. Reflecting much of the same architecture naturally lends itself to sharing address formats too.
Due to these shared characteristics, you can use MetaMask to interact with other EVM-compatible networks using the same address. This includes networks such as:
- Polygon
- BSC (BNB Chain)
- Fantom
- Avalanche (C-Chain)
Try it out: add a network to MetaMask, or switch over from one you've already added. Notice how your account and its address stay the same. This means your MetaMask address on both Ethereum Mainnet and BSC, for example, is exactly the same.
However, the interplay of networks and tokens (particularly the question of ERC-20 variants of native tokens) can be complex and is not without risk, so please always do your research before sending a transaction. A network's native tokens are unlikely to be interchangeable with the (ERC-20) version that you can send and receive on MetaMask, for example.
Interacting with networks that have different address formats: be careful!
Always do your research before sending tokens between networks to ensure they're going to the right address.
While MetaMask is a flexible passport to accessing Ethereum and EVM-compatible chains, there are some cases where you need to exercise caution when it comes to address formats:
- EVM-compatible networks with different formats. Just because a network is EVM-compatible does not necessarily mean it uses a 0x address in all circumstances. You can find the address format for any network you've enabled in MetaMask by clicking on your account details in the homepage of your wallet once you've switched over to the network. Copy your address easily to avoid mistakes by clicking on the copy icon next to it.
- Non-EVM-compatible networks: be vigilant. As flexible as MetaMask is, non-EVM networks (like Bitcoin) have a completely different blockchain architecture that MetaMask wasn't originally built to support. However, interoperability features like MetaMask Snaps now allow you to connect to non-EVM networks like Starknet directly with your wallet which you can learn more about and enable here.