What is a Seed Phrase?
A seed phrase (also called a recovery phrase or mnemonic phrase) is a list of 12 or 24 ordinary English words that backs up your entire Bitcoin wallet. Words like "apple," "river," or "flame" might appear in your phrase. Together, in a specific order, they encode everything you need to recreate every private key your wallet will ever generate.
Each private key controls a single Bitcoin address. Your seed phrase can reproduce all of them. If your phone breaks, your computer dies, or your hardware wallet burns in a fire, you enter those 12 or 24 words into a new device and get your bitcoin back.
Why It Matters
If you hold your own bitcoin (self-custody), your seed phrase is the most important piece of information you have. Lose it and you could lose access to your funds permanently. You cannot call customer support, reset a password, or ask a bank to reverse anything. Bitcoin only recognizes valid private keys, and your seed phrase is the source of all of them.
So protect it. Do not photograph it, type it into a website, or paste it into a chat message. Do not store it in a notes app, a cloud drive, or an email draft. Any digital copy can be hacked, synced to servers you do not control, or exposed in a data breach. Write the words down on paper (or stamp them into metal for durability) and store that backup somewhere physically secure, like a safe or a safety deposit box.
Anyone who sees your seed phrase can regenerate your private keys and move your bitcoin to their own wallet within seconds. For a step-by-step walkthrough of setting up your first wallet and backing up your seed phrase, see our How to Buy Bitcoin guide.
How It Works
When you create a new Bitcoin wallet, the software generates a large random number. It then converts that number into a sequence of words using a standard called BIP-39. BIP-39 defines a list of exactly 2,048 English words, each chosen to look distinct from the others (so "cat" and "car" would not both appear, for example). Your wallet picks words from this list based on the random data, and the final word includes a built-in checksum to catch transcription errors.
The order of the words matters. "apple river flame" and "river apple flame" produce completely different keys. Swap even two words and you get a different wallet with different addresses and a different balance. Always number the words when you write them down, and double-check the order before you put your backup away.
From your seed phrase, the wallet software derives a master seed (a long number), and from that master seed it generates a tree of private keys and their corresponding public addresses. This process is called deterministic key derivation: the same input always produces the same output. Enter those same 12 or 24 words into any BIP-39-compatible wallet, in the same order, and you will get the exact same keys. Most modern wallets use the same derivation standards, so your addresses and balances appear automatically. If a wallet uses a different derivation path, you may need to select the correct one to see your funds. You are not locked into a single wallet app or manufacturer.
How to Store It Safely
Paper backup. Use the recovery card that comes with your wallet. Write each word clearly, number every word (1 through 12 or 24), and double-check spelling and order before putting it away. Use a pen, not a pencil. If your wallet did not include a card, a plain sheet of paper works.
Metal backup. Paper burns, dissolves in water, and degrades over time. Stamped or engraved metal plates survive all three. Products like Cryptosteel, Billfodl, or a simple titanium stamp kit let you press each letter into stainless steel. They cost $30 to $80 and last decades.
Where to keep it physically. A home safe, a safety deposit box, or two separate secure locations all work. Do not store your seed phrase next to your hardware wallet. If a thief or a fire takes both at once, the backup did nothing for you. Two copies in two different locations give you redundancy.
Test your backup. Before loading significant funds onto a new wallet, restore the wallet from your seed phrase on a different device. This confirms the words are correct and in the right order. Five minutes of testing now can save you from discovering a bad backup when you actually need it.
Common Mistakes
- Taking a photo or screenshot. Your phone syncs photos to iCloud, Google Photos, or other cloud services automatically. That puts your seed phrase on a remote server you do not control.
- Storing it in a notes app, email draft, or cloud document. If someone compromises your account, they can read every digital copy. Hackers target these services regularly.
- Sharing it with anyone for any reason. No legitimate company, wallet provider, or support agent will ever ask for your seed phrase. Anyone who asks is trying to steal your bitcoin.
- Entering it on a website or in a message. Every "enter your seed phrase" prompt online is a scam. Real wallets only ask for your seed phrase during a recovery process on the device itself.
- Writing the words in the wrong order. One word out of place creates a completely different wallet, or no valid wallet at all. Always number your words.
- Skipping a backup test before loading funds. You will not know your backup is wrong until you try to restore from it. Test it before you send any bitcoin.
- Keeping only one copy. One copy means one point of failure. Make two and store them in separate locations.
- Storing it right next to the wallet device. If a thief or a fire takes both at once, you have lost your bitcoin and your backup together.
What Happens If You Lose It
If you lose your seed phrase and also lose access to your wallet device (it breaks, gets stolen, or stops working), your bitcoin is gone permanently. Nobody can recover it for you. Self-custody means you have full control, and that also means you carry full responsibility for your backup.
An estimated 3 to 4 million BTC are permanently lost, much of it from lost keys and seed phrases during Bitcoin's early years. Some of those coins are worth hundreds of millions of dollars today. The former holders cannot access them.
If you still have access to your wallet device (your phone, computer, or hardware wallet), you can still send your bitcoin even without the seed phrase. But you are operating without a backup. If that device fails, everything is gone. If you have lost your seed phrase but still have wallet access, create a new wallet immediately, write down the new seed phrase, and transfer all your bitcoin to the new wallet.
Planning for Inheritance
If you hold bitcoin, someone you trust needs to know your seed phrase exists and where to find it. Without a plan, your heirs cannot access your bitcoin after you die.
You can leave a sealed envelope with a trusted family member, a lawyer, or in a safe alongside your will. Write a letter of instructions that explains what a seed phrase is, where yours is stored, and how to use it. Dedicated Bitcoin inheritance planning services also exist if you want a more structured setup.
Whatever method you choose, write clear, step-by-step instructions for a non-technical person. Explain what a wallet is, which wallet software to download, and exactly how to enter the seed phrase to recover the funds. The person reading your instructions may have never touched bitcoin before. Our Best Bitcoin Wallets guide can help them choose a wallet to restore into.
Seed Phrase vs. Private Key vs. Password
These three terms overlap enough to cause confusion. Here is how they differ.
Seed phrase. The master backup for all of your private keys. You write it down once when you create a wallet. Your wallet software can recreate every key and address from this single phrase. If you have your seed phrase, you can recover everything.
Private key. A cryptographic key for one specific Bitcoin address. Your wallet derives private keys from your seed phrase automatically. In modern wallets, you never see or handle a private key directly. It works behind the scenes to authorize transactions.
Wallet password or PIN. This protects access to your wallet app or hardware device. It is not a backup. If you forget your PIN but have your seed phrase, you can restore everything on a new device. If you have your PIN but lose your seed phrase, you are one device failure away from losing everything.
Frequently Asked Questions
Can someone guess my seed phrase?
No. The BIP-39 word list has 2,048 words, and a 12-word phrase draws from that list in sequence, so there are 2,048^12 possible combinations. Brute-forcing that many possibilities would take far longer than the age of the universe.
Is 12 words secure enough?
Yes. 12 words give you 128 bits of entropy. No existing computer can crack that through guessing. A 24-word phrase doubles the entropy to 256 bits, but 12 words already exceeds what any attacker can feasibly try.
Should I split my seed phrase and store halves in different places?
Splitting is risky because losing either half means losing everything. Store complete copies in two separate secure locations instead. That way, losing one copy still leaves you with a full backup.
Can I change my seed phrase?
No. Your seed phrase is set when you create your wallet. To get a new one, you would create a new wallet, write down the new seed phrase, and transfer your funds from the old wallet to the new one.
What if my hardware wallet company goes out of business?
Your seed phrase works with any BIP-39-compatible wallet. You are not locked into any single company or product. If your wallet manufacturer disappears, restore your seed phrase in a different compatible wallet and your bitcoin will be there.
What is a passphrase or 25th word?
An optional extra password you add on top of your seed phrase. It creates a completely separate set of wallets and addresses. If someone finds your seed phrase but does not know the passphrase, they cannot access the passphrase-protected wallets. Most people do not need this; it is an advanced feature.