A seed phrase (also called a recovery phrase) is a list of words that can restore a crypto wallet and everything in it. Anyone who has the words can take the funds, and if you lose them, nobody can recover the wallet for you.
Education only, not financial, legal or tax advice. Facts on this page were checked in October 2026 against the sources listed at the bottom. See our disclosures.
What a seed phrase is
A seed phrase is a human-readable backup of the secret behind a crypto wallet. Most wallets follow a standard called BIP-39. Under that standard, the words come from a fixed list of 2,048 words, and a phrase is 12, 15, 18, 21 or 24 words long. Many hardware wallets default to 24 words.
The wallet app or device does not store your coins. The coins live on the blockchain. The seed phrase is what lets a wallet prove they are yours, which is why it works the same on a new phone or a new device.
Why it matters so much
- Whoever has the words controls the wallet. A 12- or 24-word phrase gives full access, and transfers made with it generally cannot be reversed (Switzerland’s National Cyber Security Centre).
- There is no password reset. If the words are lost and the device breaks or is stolen, the funds are gone.
- The order and spelling matter. Write every word in the order it is shown.
The optional passphrase (sometimes called the “25th word”)
BIP-39 lets you add an extra passphrase. A different passphrase produces a completely different wallet from the same words, and an empty passphrase produces the default one. This adds protection if someone finds your words, but it also adds a second thing you can lose. If you use one, back it up separately from the seed phrase (Coldcard).
How to store it safely
- Write it by hand, in order, and check it. Number each word. If you are unsure of a word, the first four letters of each word are enough to find it on the BIP-39 list (Coldcard).
- Keep it offline. Do not take a photo or screenshot, and do not type it into a computer, a notes app, a password manager or cloud storage (Casa, Coldcard).
- Use something durable. Paper is fine for small amounts or a temporary backup. For savings, Casa and Coldcard recommend metal, because paper can burn, get wet or fade. Coldcard’s maker sells metal backups, so weigh that advice accordingly.
- Keep more than one copy in different places. One backup is a single point of failure. Examples given by Casa and Coldcard: a home safe plus a bank safe deposit box, or a trusted relative’s home.
- Make sure nobody can see you write it. Casa advises making sure no one else is present and that nobody can see your screen while you write it down.
- Test the backup before you put real money in. Send a small amount, reset the wallet, restore it from the written words, and confirm the same receive address appears. Repeat the check once a year (Coldcard).
Mistakes to avoid
- Saving the phrase in email, photos, a cloud drive or a notes app.
- Keeping the phrase and the hardware wallet in the same place.
- Typing it into any website or app because it “asks to verify your wallet.”
- Storing the only copy somewhere that can burn or flood.
- Forgetting to tell a trusted person that a recovery plan exists, so heirs could not find the funds.
Seed phrase scams: nobody legitimate will ask for it
Seed phrase theft is a common scam. Switzerland’s National Cyber Security Centre describes several versions:
- Fake letters that appear to come from a wallet provider, claim a “security update” is needed and send you to a copy of a real site that asks for your phrase.
- Phishing emails that impersonate exchanges and wallet makers, claiming a blocked account or an “airdrop.”
- Phone calls from numbers that look like official support, pressuring you to read the words out loud or enter them on a website.
The centre’s advice is simple: never give out your seed phrase, because no legitimate party will ask for it. If someone pressures you, stop. Do not click links; type the company’s address into your browser yourself. If you lose money, report it to the police.
Frequently asked questions
Is a seed phrase the same as a password?
No. A password can usually be reset by the company. A seed phrase is the wallet itself, and there is no one to reset it.
12 words or 24 words?
Both are valid BIP-39 lengths. Many hardware wallets default to 24 words, but the more important point is storing whichever you have safely.
Can I store my seed phrase in a password manager?
Coldcard advises against it, and Casa advises against any internet-connected digital storage. Keep it offline.
What if I lose my seed phrase but still have the wallet?
If the wallet still works, move your funds to a new wallet and back up the new phrase right away, then test the backup.
Do exchanges use seed phrases?
If you keep coins on an exchange, the exchange holds the keys and you sign in with an account. A seed phrase is for wallets you control yourself.
Want a printable version? Our free 7-Minute Stablecoin Safety Checklist covers backups, test transfers and common scams.
Sources
- Switzerland National Cyber Security Centre (NCSC), Seed phrase theft campaign. Checked October 2026.
- Casa Support, How to safely obtain and store your seed phrases. Checked October 2026.
- Coldcard (Coinkite), How to store a seed phrase. Checked October 2026. The publisher sells metal backups.
- Learn Bitcoin, BIP-39 glossary entry. Checked October 2026.