A word on your seed phrase you can’t read

A recovery phrase written in a hurry, years ago, in pencil, tends to have one word that no longer reads cleanly. It is the most common way a backup fails, and it is usually the easiest to fix — because the word you wrote was never free text. It came from a list.

Almost every wallet uses the same list. The standard is called BIP39, and its English list has exactly 2,048 words. Ledger, Trezor, MetaMask, Trust Wallet, Exodus, Phantom and most other wallets draw every word of your phrase from it. So the question is not "what could this word be?" but "which of these 2,048 is it?" — and that is a much smaller question.

The first four letters decide it. The list was designed so that no two words share their first four letters. If those four are legible, the word is known, however smudged the rest is: "aban" can only be abandon, "wago" can only be wagon. Some metal backup plates stamp only the first four letters for exactly this reason, and wallets accept them.

When the first four are the problem, think about handwriting, not typing. A misread word is rarely a random mistake. It is a letter your hand makes that looks like another: a and o, n and u, g and y, l and t, rn and m, e and c. "Wayon" is almost certainly wagon. "Rnango" is mango. Try the readings your own handwriting allows, and check each against the list — the BIP39 word checker does this one word at a time and ranks look-alike letters as closer than arbitrary typos.

If two readings are both real words, the checksum can often choose. The last word of a phrase carries a checksum over all the others, so most substitutions produce a phrase that is not internally valid. If "cart" and "card" are both possible for one word, typically only one of them makes the whole phrase check out. The offline checker tests this on your own computer with the internet disconnected, which is the only safe place to do it. How the checksum works explains why this narrows things so sharply.

A valid checksum still is not proof. It means the phrase is well-formed, not that it is yours. The proof is an address: restore the phrase in your wallet software, offline if you can, and confirm it produces an address you know held your funds — from an old transaction, an exchange withdrawal record, or a screenshot.

If the word is not on the list at all, check which scheme you have. Electrum's own seeds use a different checksum from BIP39, very old Electrum versions used a different list entirely, and Monero uses 25 words from its own list. A phrase from those will look nearly right and never validate as BIP39. The wallet that made it is the only thing that can check it.

What not to do. Do not type the phrase — or most of it — into any website to "check" it, ours included. This site's word checker takes one word and refuses more. Anyone who asks for the whole phrase, whatever they call themselves, is asking for the funds. How to spot a recovery scam is worth five minutes before you talk to anyone.

When one word turns into several. If more than one word is uncertain, or the order is in doubt too, checking by hand stops being practical quickly. That is a search with a definite answer when you have an address to test against, and it is what our offline recovery toolkit runs on your own machine.