Never type a real seed phrase into a website
Your recovery phrase is the wallet. Anyone who sees it can take every coin, on every chain the wallet supports, and no one can reverse it. Legitimate wallet support, exchanges and tools will never ask for it. Phishing sites very often look exactly like a “seed phrase checker” or a “wallet sync” page — that is how they collect phrases.
That is why this tool works with one word at a time and shows a warning if several list words are pasted together. Use it to confirm the spelling of a word on your backup sheet, or to find the number of a word if you are engraving a metal backup that uses numbers. Do it on a device you trust, and do not paste whole phrases anywhere — including here.
How to use the lookup
Type one word, its first four letters, its number from 1 to 2048, or an 11-bit binary value. You get the word, its line number in the official english.txt file, its zero-based index (the value actually encoded in the mnemonic), the 11-bit binary form and the four-letter prefix. If the word is not in the list, you get the closest matches — handy for spotting a misspelling such as “abandn” → “abandon”. Typing fewer than four letters shows all words that start with them.
Facts about the BIP39 English list
- 2048 words = 2¹¹, so each word encodes exactly 11 bits.
- The list is sorted alphabetically: word 1 is “abandon”, word 2048 is “zoo”.
- The first four letters of every word are unique, so a backup can store just four letters per word.
- Words are 3 to 8 letters long and chosen to avoid confusingly similar spellings.
- A 12-word phrase holds 128 bits of entropy plus a 4-bit checksum (132 bits); 24 words hold 256 bits plus 8 checksum bits (264 bits).
- Because of the checksum, a random set of 12 list words is usually not a valid phrase — wallets reject it.
How a mnemonic is built
A wallet first generates random entropy, appends a few bits of its SHA-256 hash as a checksum, splits the result into 11-bit groups and maps each group to a word by index. The words, plus an optional passphrase, are then stretched with PBKDF2-HMAC-SHA512 into the seed that derives all your keys. The index shown by this tool is that 11-bit group.
entropy (128–256 bits) ‖ SHA256(entropy)[first ENT/32 bits]
→ split into 11-bit groups → word = list[group]
seed = PBKDF2-HMAC-SHA512(mnemonic, "mnemonic" + passphrase, 2048 rounds)Backup tips that actually matter
Most lost wallets are lost to bad backups, not to hackers. A few habits help:
- Write the words by hand in order, with numbers, and double-check each spelling against the list.
- Store at least two copies in different physical places; consider a fire-resistant metal backup.
- Never photograph the phrase, store it in cloud notes or email it to yourself.
- Test the backup by restoring the wallet on a trusted device before funding it heavily.
- If you suspect the phrase was exposed, create a new wallet and move the funds immediately.
Passphrase (25th word) and why it matters
BIP39 allows an optional passphrase that is mixed into the seed. The same 12 or 24 words with a different passphrase produce a completely different wallet. This adds protection if someone finds your written words, but it also adds a risk: forget the passphrase and the funds are gone, because nothing in the word list can recover it. If you use one, back it up separately from the words and test the restore before relying on it.
Download the word list
The TXT file above is the official English list, one word per line in order — identical to english.txt in the BIP39 repository (SHA-256 checked). The CSV adds the index (1–2048), the zero-based index and the 11-bit binary value, handy for checking a metal backup or teaching how mnemonic encoding works. Both are free direct downloads. The list is public; your phrase is not — never put your words into a file on an internet-connected device.
Frequently asked questions
+How many words are in the BIP39 word list?
2048 words. Each word represents 11 bits, because 2¹¹ = 2048.
+What is the first and last word of the BIP39 list?
The first word is “abandon” (number 1, index 0) and the last is “zoo” (number 2048, index 2047).
+Can I check my seed phrase here?
No — and you should not check it on any website. This tool looks up single words only. Validate a phrase only inside the wallet software or hardware wallet you trust.
+Are the first four letters enough to identify a word?
Yes. In the English list the first four letters of every word are unique, which is why many metal backups store only four letters.
+Is the list the same in every wallet?
Wallets that follow BIP39 use the same English list. Other languages have their own lists, and some wallets (for example Electrum's native seeds or Monero) use different schemes.
+Can I download the template for free without registration?
Yes. The TXT / CSV file is a direct link on this page: no account, no e-mail and no payment. You can also use the online version above and export your own numbers.
Calculations run entirely in your browser; nothing you type is sent to KOT.CASH. Results are estimates for information only and are not financial, tax or legal advice.