Calculadora de Força de Senha Online Grátis
Password entropy, strength score, crack time estimate and improvement tips
The Password Strength Calculator measures your password's entropy in bits, assigns a strength score from 0–100, and estimates how long it would take to crack using a brute-force attack at modern GPU speeds. Security professionals, IT policy writers, and anyone curious about whether their passwords actually stand up to attack will find the detailed breakdown useful.
Frequently Asked Questions
Sobre Esta Calculadora
Password strength is not about how complex a password looks to a human — it's about entropy: the mathematical measure of how many possible combinations an attacker must try. A password that seems complex ("P@ssw0rd!") can be trivially cracked because attackers use rule-based mutation lists that already include common substitutions.
This calculator evaluates entropy based on character set size and length, checks for common patterns and dictionary words, and translates the result into an estimated crack time at realistic attack speeds (10 billion guesses/second for a dedicated GPU rig). The strength score accounts for both raw entropy and pattern vulnerabilities.
IT administrators use this to enforce evidence-based password policies — replacing arbitrary "must include a number" rules with minimum-entropy requirements. Individuals use it to understand which of their stored passwords are weakest and should be replaced first.
A Calculadora de Força de Senha mede a entropia e classifica o nível de segurança da sua senha.
Exemplo Resolvido
Comparing two passwords of the same length
Entradas:
- Password A: "password123" (11 chars, lowercase + digits)
- Password B: "kR7@mP2#xL9" (11 chars, mixed case + digits + symbols)
Passo a Passo:
- Password A character set: 26 lowercase + 10 digits = 36 characters
- Password A entropy: 11 × log₂(36) = 11 × 5.17 = 56.9 bits
- Password B character set: 26 + 26 + 10 + 32 symbols = 94 characters
- Password B entropy: 11 × log₂(94) = 11 × 6.55 = 72.1 bits
- Crack time at 10 billion guesses/sec: A ≈ 3.7 hours | B ≈ 62 years
Dicas
- A 12-character password with mixed case, numbers and symbols would take centuries to crack by brute force.