BIP39 Words Entropy Strength Check
BIP39 word count layout only; does not validate wordlist/checksum, randomness, recovery ownership or wallet safety.
Description
Map a permitted BIP39 word count to entropy, checksum and encoded bit lengths.
A BIP39 mnemonic's permitted word count encodes an entropy length plus a checksum length. This lookup reports those lengths from the count alone.1
When to use this tool
Map a permitted BIP39 word count to entropy, checksum and encoded bit lengths. Use it when the input measurements and conventions below match the operation you need.
- Prepare wordCount, respecting the measurement basis and boundaries below.
- Compare the worked example with your intended operation before reusing its result.
How to use the tool and how it works
- Enter every field in the input table using the stated units and exact supported selector spelling where applicable.
- Run the tool. Correct input errors before interpreting an output.
- Read the result fields below; use accompanying flags and the stated sign, boundary or model convention when interpreting a number.
Select 12, 15, 18, 21 or 24 words exactly as supported. Entropy lengths are 128, 160, 192, 224 or 256 bits; checksum length is entropy divided by 32 and total bits are their sum. validMnemonicVerified is always false.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| wordCount | Word count. | Number: 12, 15, 18, 21 or 24 |
| Output field | Interpretation |
|---|---|
| result | Object containing the following named result fields. |
| result.entropyBits | Entropy bits; use the stated units and sign convention. |
| result.checksumBits | Checksum bits; use the stated units and sign convention. |
| result.totalEncodedBits | Total encoded bits; use the stated units and sign convention. |
| result.validMnemonicVerified | Always false; neither word membership nor checksum is checked. |
{
"input": {
"wordCount": 12
},
"output": {
"result": {
"entropyBits": 128,
"checksumBits": 4,
"totalEncodedBits": 132,
"validMnemonicVerified": false
}
}
}Limitations and assumptions
- No words, checksum, seed or wallet are examined. A permitted word count does not establish a valid mnemonic or secure entropy generation.
- Every declared field is required and unexpected fields are rejected. Numeric inputs must be finite; input errors are distinct from a valid false result or an explicitly qualified output.
- Extremely large inputs and nonfinite or excessively large outputs are rejected. List positions reported by the tool use zero-based indices unless stated otherwise.
Alternative or Complementary methods
Use the applicable protocol specification and a reviewed implementation for real verification, hashing or key management. A format label, probability model or tentative text mapping does not replace that operation. Compare the scope of the nearby tools below before substituting one.
References
-
BIP 39: Mnemonic code for generating deterministic keys — BIP authors: Marek Palatinus, Pavol Rusnak, Aaron Voisine and Sean Bowe
-
Tool behavior and example: BIP39 Words Entropy Strength Check — tool.io
Similar or alternative tools
- diceware words to entropy bits
A Diceware-style passphrase gains ideal entropy from independent uniform selections in a word list.
- entropy bits from charset length
Ideal entropy for independent uniform character choices is the logarithm of the number of possible strings.