When to use this calculator
Measure the theoretical information content of a uniform random character model. Applies only to uniformly independent random choices. Human-created passwords generally do not meet this model.
Explore the storage & compression calculators for other questions in this topic. For a related calculation, use the Storage Saving Percentage Calculator: Find the percentage of original data size saved after compression.
PUTTING IT INTO PRACTICE
Password Search Space Bits: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Alphabet size (integer) | 64 |
| Independent random characters (integer) | 12 |
| Result | 72 bits |
- Check the input labels and enter the example values above.
- Apply the relationship: Ideal entropy bits = length × log₂(alphabet size).
- The result is 72 bits, rounded for display.
How to interpret your result
Applies only to uniformly independent random choices. Human-created passwords generally do not meet this model.
Specify decimal or binary units before comparing storage totals. Full-backup retention differs from incremental or deduplicated backup plans. Compression can sometimes increase size when data is already compressed.
Frequently asked questions
Is a 4:1 compression ratio a 400% saving?
No. It means the compressed size is one quarter of the original, corresponding to a 75% size reduction.
When is the password search space bits calculator useful?
Measure the theoretical information content of a uniform random character model. Applies only to uniformly independent random choices. Human-created passwords generally do not meet this model.
How do I use the password search space bits calculator?
Enter alphabet size (integer), independent random characters (integer). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Ideal entropy bits = length × log₂(alphabet size).
What should I check before using the result?
Applies only to uniformly independent random choices. Human-created passwords generally do not meet this model.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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