Bcrypt Cost Estimator
Compare bcrypt cost factors and relative work without entering passwords.
Enter a cost factor between 4 and 18.
Understand bcrypt cost factors
Bcrypt deliberately slows down password hashing, and its cost factor controls exactly how slow — each step up roughly doubles the work. Picking it well balances security against login latency. This estimator shows the relative work of each cost factor so you can choose deliberately.
Crucially, it does no hashing and asks for no passwords — it is an educational comparison of how the cost factor scales, not a place to enter real secrets. Use it to reason about the trade-off before setting the value in your auth code.
Choosing a cost factor
A common target is a hash time near 250ms on your production hardware, raised as machines get faster. The estimate is computed locally and nothing you enter is uploaded.
Frequently asked questions
What does the bcrypt cost factor mean?
The cost is a power of two: bcrypt runs 2 to the power of cost rounds. Each step up doubles the work, so cost 12 is four times the work of cost 10.
What cost factor should I use?
Pick the highest cost that keeps a single hash around 250 milliseconds on your production hardware, and raise it as hardware gets faster.
Do I need to enter a password?
No. The estimator only compares cost factors from 4 to 18. It never hashes anything.
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