What is a seed phrase passphrase (the 25th word)?

A seed phrase passphrase is an extra word or phrase you choose and add on top of your 12 or 24 recovery words. People call it the 25th word because it sits after a 24-word phrase, though it can be longer than one word. With it, the same recovery phrase can open several separate wallets.

What is the difference between a seed phrase and a passphrase?

Your seed phrase is generated by the wallet from a fixed list of 2048 words. The passphrase is something you make up. Under BIP-39, the wallet mixes the two together to produce the master seed. If you never set a passphrase, the standard simply uses an empty one, which gives your normal wallet.

The passphrase is also different from your device PIN. A PIN only unlocks a particular device. The passphrase changes which wallet you get, on any device or app that supports it. Trezor says its devices never store the passphrase, so you type it each time.

How does a hidden wallet passphrase work?

Because every passphrase produces a valid wallet, each one opens its own set of accounts. Ledger calls these hidden accounts and Trezor calls them passphrase wallets. They start empty and only fill up when you move funds into them.

This gives two kinds of protection. Someone who finds your written seed phrase can reach only the standard wallet, not the hidden ones. And since an outsider cannot tell whether a passphrase exists, BIP-39 describes it as offering plausible deniability. Ledger notes this is only limited protection and suggests keeping a small balance in the standard wallet if you rely on it.

Details differ by device as of October 2026. Trezor allows up to 50 characters and Ledger up to 100. Both are case sensitive. Ledger can also tie a passphrase to a second PIN so it opens at startup.

What happens if you forget your passphrase?

The funds in that hidden wallet become unreachable. Trezor states that passphrases cannot be changed, removed or recovered, and Ledger says it does not store or back them up. Your recovery phrase alone will not bring them back.

Typos are the most common trap. Enter one wrong character, or a capital letter where there should be none, and the wallet opens a different, empty wallet with no warning. Your money is still safe, just in the wallet you meant to open.

Should you write the passphrase down?

Trezor suggests memorizing it, or, if you write it down, storing it separately from your recovery phrase with the same care. Keeping both together defeats the purpose. Trezor also warns against simple choices like "password" and says to test access regularly.

Passphrases are not required, and both makers present them as advanced features. If you are still learning, start with what to do if you lose your seed phrase and our guide to a broken or lost hardware wallet.