---
title: "Why the BIP39 Wordlist Has Exactly 2,048 Words (PDF)"
url: "https://bip39-phrase.com/list-phrase/seed-phrase-list-eng-19-february-2025/"
language: "en"
updated: "2026-10-18T00:00:00+00:00"
---

# Why the BIP39 Wordlist Has Exactly 2,048 Words

BIP39 uses a 2,048-word dictionary so each word encodes exactly 11 bits of entropy, balancing phrase length with human usability and error prevention.

PDF document · Published February 19, 2025 · Updated October 18, 2026 

[ Open the PDF (6 pages, 188 KB) ](/list-phrase/seed-phrase-list-eng-19-february-2025.pdf) 

## Contents

1. The Mathematics of 11 Bits per Word
2. Trade-offs Between Dictionary Size and Phrase Length
3. Linguistic Constraints and Collision Avoidance
4. Hardware and Implementation Constraints
5. FAQ
6. Sources

Keywords: 

seed phrase · entropy · mnemonic

Topic: 

[Seed Phrases: Creating, Storing and Protecting Them](/topics/seed-phrases/)

## Guides on the same subject

- [Seed Phrase Examples: 12, 18 and 24 BIP39 Mnemonic Phrases](/mnemonic-words-examples-for-crypto-security-bip39/)  
Real BIP39 seed phrase examples for 12, 18 and 24 words from the official test vectors, with their entropy, checksum bits and why random words fail.
- [12 vs 24 Word Seed Phrase: Which Is More Secure?](/12-vs-24-word-seed-phrase/)  
A 24-word seed phrase has 256 bits of entropy and a 12-word one 128, but both are beyond brute force; 24 words help mainly when part of a backup is exposed.
- [BIP39 Passphrase: How the 25th Word Creates a Hidden Wallet](/bip39-passphrase/)  
A BIP39 passphrase, the 25th word, is mixed into the seed, so the same words open a separate hidden wallet; a typo opens an empty one, so back it up exactly.

One of the documents in the [Seed Phrase PDF Archive](/list-phrase/), listed on [archive page 1](/list-phrase/1/).