How to Hash a Password with Bcrypt (2026)

Bcrypt is the most widely recommended algorithm for hashing passwords. Unlike general-purpose hash functions such as SHA-256, bcrypt is deliberately slow — its cost factor lets you tune work to keep brute-force attacks expensive even as hardware improves. Use the Bcrypt Simulator to hash a password and verify hashes instantly, entirely in your browser.

How Bcrypt Works

Bcrypt applies a modified Blowfish cipher in a loop controlled by a cost factor (also called rounds or work factor). Each increment of the cost factor doubles the computation time. The output is a 60-character string that encodes the algorithm version, cost factor, salt, and hash together — so you only need to store one value per password.

A bcrypt hash looks like this: $2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW. The $2b$ prefix is the version, 12 is the cost factor, the next 22 characters are the Base64-encoded salt, and the remaining 31 characters are the hash.

Choosing the Right Cost Factor

The cost factor controls how long a single hash takes. The goal is to make hashing slow enough to deter brute force, but fast enough not to degrade your login UX. A good target is 100–300ms per hash on your production hardware. The table below shows typical timings on modern server hardware.

OWASP recommends a minimum cost factor of 10, with 12 being the current practical standard. Increase by 1 every 18–24 months to keep pace with hardware improvements.

Hashing and Verifying in Code

Most languages have a well-maintained bcrypt library. The pattern is always the same: hash once on registration, verify on login — never compare plaintext passwords directly.

In Node.js with bcryptjs:

// Hash (registration)
const hash = await bcrypt.hash(password, 12);

// Verify (login)
const match = await bcrypt.compare(input, storedHash);

In Python with bcrypt:

# Hash
hashed = bcrypt.hashpw(password.encode(), bcrypt.gensalt(rounds=12))

# Verify
match = bcrypt.checkpw(input.encode(), hashed)

Never log, store in plaintext, or transmit hashes over insecure channels. Use the Bcrypt Simulator to test cost factors and verify hashes without writing any code.