What Is a Seed Phrase? The 12 Words That Own Your Crypto
A seed phrase is the 12 or 24 words that can rebuild your whole crypto wallet. Here is how it works, where to keep it, and who will try to get it.
Key takeaways
- Your crypto wallet can be restored from a seed phrase that consists of between 12 and 24 common words across all compatible apps.
- Nobody can realistically guess one, but anyone who sees it can empty the wallet, so how you store it matters more than how long it is.
- A seed phrase should be stored offline in two places, written down and never entered into any app or website that requests it.
- There is no reset button. If the device and a seed phrase are both lost then the associated funds are also lost.
When creating a crypto wallet you were shown a list of words and were told to store them. Most people write the words down and continue with their use of the wallet. These words are the most important part of the crypto wallet. Below we explain what they are and how to store them.
What is a seed phrase?
A seed phrase is created when a crypto wallet is first created. The format of a seed phrase uses BIP-39 which was created in 2013 and is used by most wallets that support self-custody. A seed phrase may also be referred to as a recovery phrase, a secret recovery phrase or a mnemonic. All of these refer to the same thing.
What it is
- A backup of all keys used in a wallet
- 12, 15, 18, 21 or 24 words in a specific order
- Words selected from a list of 2,048 words
What it is not
- A password that can be reset or changed
- Something held by the wallet company
- Something that should be entered into a website
How a seed phrase works
When creating a crypto wallet a random number is taken and converted into words that can then be written by the user. These words are then converted back into a master number (seed) which is then used to generate all the keys in a wallet.
The check included in the creation of a random number is also why it is not recommended to create your own words. Only approximately one in every 16 random sets of 12 words would pass the check. Words that are chosen by a user are also far less random than those chosen by a wallet.
Seed phrase vs private key
Both can give someone your crypto, but not to the same extent.
Can someone guess a seed phrase?
Not by guessing. We have calculated the time it would take to guess a phrase. The numbers involved are so large that the biggest risk of a compromised seed phrase is not a guess but a reveal of the words in the phrase.
How seed phrases really get stolen
- A photo or screenshot that synced to the cloud
- A note or text file on a computer that later gets malware
- A fake support agent or website that asks you to type it in
- Someone who finds the paper
12 or 24 word recovery phrase: which is safer?
Both lengths are far too large to be guessed. 12-word seed phrases are quicker to write and check which is important as a single incorrect word in a seed phrase can result in a wallet being locked. 24-word seed phrases offer a greater safety margin if one is desired. Either option requires that the phrase be kept private regardless of number of words.
Recovery phrase example and the word list
We downloaded a copy of the official English list of words used in seed phrases and checked all 2,048 of the words ourselves.
- 1ocean
- 2verify
- 3ladder
- 4pumpkin
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
Seed phrase storage: how to keep it safe
In a September 2024 warning from the FBI's Internet Crime Complaint Center it was stated that seed phrases or private keys should not be stored on any devices that are connected to the internet. Below we show one way to do this securely.
-
Write your seed phrase by handWrite out all the words in the order they appear in the wallet in clear handwriting.
-
Check each wordRecheck all the words against the wallet displaying them before closing the wallet.
-
Create a second, more secure versionMetal which has been engraved or stamped is far more resilient to flood or fire than paper.
-
Store the two versions separatelyStore the two versions separately so one flood, fire or house move does not compromise both copies.
Common seed phrase myths
-
Myth
Support for my wallet may require a seed phrase from me.FactReputable wallet support will not require a seed phrase. Anyone that does require a seed phrase is after your funds.
-
Myth
My gallery screenshot is private.FactScreenshots may be automatically synced to the cloud by many phones. This means your screenshot may not remain on your device.
-
Myth
If lost it can be reset by the wallet provider.FactWith a self-custody wallet no one else has a copy so there is no reset.
-
Myth
I can make up my own 12 words.FactCustom user created seed phrases are far less random. Additionally most custom seed phrases will fail the included check.
The seed phrase scams to know
-
Fake support
A third party claims to be able to resolve a problem with your wallet and asks for your seed phrase in order to do this.
-
Phishing pages and apps
A copy of a wallet page asks you to import, sync or verify your seed phrase. Any text that you enter will be passed on to the scammer.
-
Free seed phrases with a balance
These deals cannot work as advertised. A seed phrase that holds funds belongs to someone and that person will transfer those funds not give them away.
-
Recovery scams
Someone offers a service in which they will get your crypto back for a fee. The FTC notes that crypto payments are typically not reversible. Therefore these services can result in one loss becoming two.
What happens if you lose your seed phrase?
If a wallet can still be accessed then there is no immediate issue. Create a new wallet, store the seed phrase for this new wallet properly and transfer your funds over. If both the device and your seed phrase are lost then there is no recovery as no one else holds your keys.
The optional passphrase
Some wallets allow for a passphrase to be added on top of the seed phrase. A seed phrase with a different passphrase will open a completely different wallet. This provides an additional layer of security if a seed phrase is compromised and an additional thing to lose as a forgotten passphrase cannot be recovered.
Where Senton Wallet fits
Senton Wallet is next in our feature pipeline. It is a self-custody wallet that is not yet available. The goal is to have your seed phrase created and stored on your device. We would not hold a copy of a seed phrase and therefore could not reset a seed phrase.
The bottom line
- A seed phrase consists of between 12 and 24 words that can recreate your entire wallet.
- It is not realistic to guess such a phrase, but it can be revealed or handed over.
- Write it down and check it. Store two copies of it in separate locations offline.
- Reputable wallet support does not require a seed phrase so it should not be shared.
Frequently asked questions
No. A single private key controls a single address. A seed phrase can recreate all the private keys in a wallet so more care is needed.
Yes. Each word represents a number in a specific order. The final word also contains a check that would usually reject a seed phrase in the wrong order.
Not for an existing wallet. If the seed phrase may have been seen then create a new wallet and transfer your funds over to this new wallet.
Most wallets that support BIP-39 can also restore a seed phrase created by another wallet. Some wallets will search for accounts in different places so a restored wallet may initially appear empty even if funds are still present.
Not in practice. A 12-word seed phrase would take approximately 10¹⁹ years to guess at 1 trillion guesses per second. Seed phrases are typically compromised due to them being seen, stored online or handed over.
Safer than a notes app or a photo as it is encrypted. It is still stored on a device that is connected to the internet which the FBI has advised against. An offline paper or metal copy of a seed phrase is a more secure option.