What is a diceware passphrase and why is it secure?

A diceware passphrase is a sequence of random words chosen by rolling physical dice and looking up results in a word list. Each word adds ~12.9 bits of entropy. Five words gives 64+ bits — considered unbreakable by brute force — while being far easier to remember than a random character string.

How many words do you need in a diceware passphrase?

Four words (~51 bits) is the minimum for non-critical accounts. Five words (~64 bits) is the recommended standard. Six words (~77 bits) is suitable for master passwords or encryption keys that protect everything else.

What is the sentence method for creating memorable passwords?

Take a personal sentence you will remember, then build a password from the first letter of each word plus numbers and symbols. For example, 'My cat Whiskers was born in 2019!' becomes 'McWwbi2019!'. Adding capitalisation and punctuation from the original sentence makes it both strong and memorable.

Which passwords should you actually memorise vs. store in a manager?

Memorise only 2–3 critical passwords: your device login, your password manager master password, and optionally your primary email. Store everything else in a password manager. Attempting to memorise more leads to reuse and weak passwords.

Security

How to Create a Strong Password You Can Actually Remember (Diceware & Passphrase Guide)

2026 · 9 min read · ToolPry

Arun Gopal · Developer & Founder, ToolPry

Most password advice tells you to use a random string like xK9#mPq@2. You cannot remember that. So you write it on a sticky note, use your pet's name instead, or reuse the same password on twenty sites. This guide covers the only two techniques that produce passwords strong enough to resist cracking and memorable enough to actually use without a manager — diceware passphrases and the sentence method.

Why a few random words beat xK9#mPq@2: a passphrase's strength comes from how many words it is drawn from, not from symbols. With the 7,776-word EFF Diceware list, each word adds ~12.9 bits — so 4 random words is ~52 bits, 5 is ~65 bits, and 6 is ~77 bits (the threshold worth using for critical accounts). The catch is "random": the words must be chosen by dice or a generator, never by you. NIST SP 800-63B backs length over forced complexity.

If you want to test the strength of a passphrase you create here, the ToolPry password strength checker shows entropy in bits and offline crack time instantly in your browser.

Why Most Memorable Passwords Are Weak

The human brain finds patterns memorable: P@ssw0rd, Summer2024!, Fluffy123. Attackers know this. Modern GPU rigs run rule-based attacks that automatically try common words with leet substitutions (a→@, e→3, o→0) and append years and symbols. A password like S&mm3r2024! that feels complex to a human is cracked in seconds because the rule-based pattern is in every attacker's dictionary.

Length beats complexity. A 6-word passphrase like correct horse battery staple barrel fence has more entropy than a 12-character random string using letters, numbers, and symbols. The words make it memorable; the sheer number of combinations makes it uncrackable.

Method 1 — Diceware Passphrases (the gold standard)

Diceware was invented by Arnold Reinhold in 1995 and remains the most rigorously analysed memorisable password method. You roll a physical six-sided die five times per word to generate a truly random index into a 7,776-word list. Each word adds approximately 12.9 bits of entropy.

How to generate a diceware passphrase

Get a physical die (or use a cryptographically secure virtual one — not your phone's random function).
Roll five times and write down the five digits as a sequence, e.g. 24135.
Look up that sequence in the EFF Diceware word list.
Repeat for each additional word. Five words = 64 bits of entropy. Six words = 77 bits.
Use a space or hyphen between words — this is part of the passphrase and makes it slightly stronger.

Why physical dice matter: Software random number generators (including JavaScript's Math.random()) are pseudo-random and potentially predictable if seeded poorly. For diceware specifically, physical dice are the canonical method. The ToolPry passphrase generator uses the Web Crypto API which is cryptographically secure for software generation.

How many words do you need?

Words	Entropy	Offline crack time (GPU)	Memorability
4 words	51.7 bits	~3 months	Easy
5 words	64.6 bits	Millions of years	Good
6 words	77.5 bits	Longer than civilisation	Requires brief practice

Five words is the practical sweet spot for most people. Six words for anything protecting financial accounts or email (the keys to your identity).

Method 2 — The Sentence Method

The sentence method converts a memorable sentence into a password by taking the first letter of each word, with numbers and punctuation preserved naturally from the sentence itself.

Step-by-step

Think of a sentence only you would construct. Not a famous quote — something personal and specific.
Example: "My dog Max ate 3 socks on Tuesday morning!"
Take the first letter of each word, preserve the number and punctuation: MdMa3soTm!
This gives you 10 characters with upper, lower, number, and symbol — genuinely random-looking, fully memorisable.

Making sentence passwords stronger

Use a longer sentence (12–15 words gives 12–15 character output).
Include a number that's part of the narrative, not appended at the end.
Avoid song lyrics, film quotes, or proverbs — these are in attacker dictionaries.
Make the sentence specific to you: your dog's name plus a specific incident beats any generic phrase.

The weakness of the sentence method is that it produces character sequences, not truly random entropy. Attackers with knowledge of the method run "sentence-based" attacks. For your most critical accounts, prefer diceware.

Which Passwords Should You Actually Memorise?

The honest answer is: very few. A full-commitment memorisation strategy for 50 accounts is unrealistic. Here's the practical hierarchy:

Memorise: Your device login password. Your password manager master password. Your email account password (the key to everything else). Possibly your bank — though most support hardware 2FA now.
Store in a manager: Every other account. Use the manager to generate a unique 20-character random string for each site. You never need to remember these.
Never memorise across devices: Do not use the same memorised passphrase on more than one site. If one site leaks, your master passphrase is compromised everywhere.

Use diceware or the sentence method for the 3–5 passwords you genuinely need to memorise. Use a password manager for everything else. These strategies complement each other — they are not alternatives.

Testing Your Passphrase Strength

Before committing a passphrase to memory, verify its entropy. The ToolPry password strength checker accepts any passphrase and shows:

Entropy in bits (you want >60 bits for general use, >77 bits for critical accounts).
Estimated offline GPU crack time at 10 billion guesses per second.
Which character classes are contributing to — or missing from — the strength calculation.

Everything runs in your browser. Your passphrase is never transmitted. The checker is also useful for verifying existing passwords you use before switching to a manager.

The Bottom Line

Pick one method and commit: a 5–6 word Diceware passphrase you generate (not invent) for the handful of accounts you must memorise, and a password manager for everything else. Generate the passphrase with the ToolPry Password Generator and confirm it clears ~65 bits before you rely on it.