Cybersecurity

Should I Include Special Characters in Generated Passwords?

Yes—when a generator makes the password, special characters add real entropy for free. But NIST no longer lets sites force them. Here's the difference, with a decision table and a character-set entropy chart.

By Inventive HQ Team

Yes—when a password generator is creating the password, you should include special characters. They enlarge the character pool from roughly 62 characters (letters and digits) to about 94 printable ASCII characters, so every position carries more entropy and the same-length password takes exponentially longer to brute-force. The one condition is that the placement must be genuinely random, which is exactly what a generator does and a human does not. So switch symbols on by default, and only drop them for a specific system that rejects them—compensating with extra length.

That is the summary an AI overview will hand you. Here is the part it flattens: for passwords you invent, modern guidance says the opposite. NIST SP 800-63B no longer lets sites force special characters, because mandating them just produces predictable patterns like Password1!. The nuance that matters is who is choosing the characters—a random generator versus a human memory—and this article is about getting that distinction right.

The generator-vs-human distinction (this is the whole point)

Almost every argument about special characters gets muddled because two different questions are treated as one:

  1. "Should a site require special characters from users?" — Modern answer: no. Forcing humans to add a symbol yields Summer2024! and P@ssword1, patterns attackers model perfectly. NIST SP 800-63B Rev. 4 (2024) tells verifiers they shall not impose composition rules and to prioritize length instead.
  2. "Should a generator include special characters in a random password?" — Answer: yes. A generator has no memory bias, so a wider pool means genuinely more entropy per character with zero usability cost, because a password manager stores the result.

The rest of this post lives in question 2—you are using a generator—but keep question 1 in mind so you don't repeat the myth that "complexity rules make passwords strong." They don't. Randomness and length do.

Should I include special characters? A decision table

Your situationInclude special characters?What to do instead / also
Generator + password manager (the ideal)Yes, always onAlso set length to 16+; you never type it, so complexity is free
Site rejects certain symbolsUse only the accepted setIncrease length to 20+ to keep total entropy high
Human-memorized password (no manager)Optional—don't force itUse a long random passphrase (4–6 words); length beats symbols
A passphrase you must type oftenSymbols optionalAdd length/words rather than hard-to-type symbols
Legacy system, letters + digits onlyNot possibleCompensate with 20+ characters; flag the system as behind
Meeting an old "complexity" policyYes (required)Still let the generator randomize placement, not a pattern

The through-line: on a generated password stored in a manager, always include special characters. Everywhere a human has to remember or type it, prefer length over symbols.

Why the character pool matters: entropy per character

Password strength is total entropy—measured in bits, equal to the password length multiplied by the bits contributed by each character. Each character's contribution is log₂(pool size). Widen the pool and every single position gets stronger:

Character pool size and entropy per character Horizontal bars comparing four character sets: lowercase only (26 characters, 4.70 bits each), plus uppercase (52, 5.70 bits), plus digits (62, 5.95 bits), and plus special characters (94, 6.55 bits). Bars grow to their final width. More character types = more entropy per character Bar length = pool size; label = bits of entropy each character adds

a–z (26) 4.70 bits

+ A–Z (52) 5.70 bits

+ 0–9 (62) 5.95 bits

+ !@#$ (94) 6.55 bits

Adding symbols raises each character from 5.95 to 6.55 bits… …but adding one character to the length adds a full 6.55 bits. Length wins.

That last line is the honest caveat. Special characters help, but the biggest lever is length: extending a 12-character password to 13 adds more entropy than upgrading its whole character set from digits to symbols. The correct strategy is not either/or—it is both, which a generator delivers for free.

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Try it: generate a password with symbols on

The fastest way to see the difference is to generate one and watch the strength estimate move as you toggle special characters and length.

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How special characters defeat dictionary attacks (when random)

Brute-force attacks try every combination; dictionary and rainbow-table attacks are smarter—they target the patterns humans actually use: words, names, dates, and predictable substitutions. These precomputed databases contain millions of common passwords and their obvious variants, so Password123 is already in them.

Randomly placed special characters break that pattern. A symbol dropped in an unpredictable position pushes the password outside the scope of those databases and forces the attacker back to pure brute force, which is computationally infeasible against a long random string. The critical word is randomly: if you always append ! to a dictionary word, attackers simply add that rule to their toolkit. That predictability is precisely why human-chosen "complexity" is weak and generator randomness is strong.

Compatibility: the shrinking edge case

Special characters can still cause occasional friction. Some legacy systems reject certain symbols, a few web forms have encoding bugs, and outdated policy pages sometimes claim symbols aren't allowed when they actually are. These problems are real but increasingly rare—NIST explicitly says verifiers should accept all printable ASCII and Unicode characters.

For maximum compatibility, generators stick to the widely supported set: !@#$%^&*()_+-=[]{}|;:',.<>?/. Avoid obscure symbols unless you know the system supports them. When a genuine incompatibility appears, it shows up immediately as you try to save the password—so regenerate without the offending character, or lengthen the password to keep entropy high. A service that blocks common symbols is quietly telling you its security is behind the times.

Why unmemorable is a feature, not a bug

A random password full of special characters is essentially impossible to memorize—and that is the point. When a password is easy to remember, people reuse it across accounts, which is one of the most damaging security mistakes because a single breach then unlocks many services (the mechanism behind credential stuffing).

An unmemorable password forces you into a password manager, which is exactly where you want to be. Managers store hundreds of unique, maximally complex passwords and autofill them, so the usability cost of special characters drops to zero. The mild inconvenience of "I can't remember this" is doing you a favor.

The bottom line

For a generated password stored in a manager, include special characters every time: they add entropy for free, defeat dictionary attacks when randomly placed, and cost you nothing because you never type them. Just don't confuse that with the outdated idea that sites should force complexity—NIST retired that rule because human-created "complex" passwords are predictable. Get the two straight and the advice is simple: let the generator use the widest character set it can, push the length to 16+, and store the result in a password manager. Turn special characters on by default; turn them off only for a specific system that refuses them, and add length to make up the difference.

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Frequently Asked Questions

Should I include special characters in a generated password?

Yes. When a generator produces the password, turning on special characters is a free win: each character is drawn from a larger pool (about 94 printable ASCII symbols instead of 62), so every position carries more entropy and the same-length password becomes harder to brute-force. The important caveat is that this only helps because the placement is truly random. The advice is different for passwords you invent yourself—see the next question.

Does NIST recommend special characters in passwords?

No—and this surprises people. NIST SP 800-63B (Revision 4, 2024) says verifiers SHALL NOT impose composition rules such as requiring a mix of uppercase, digits, and symbols. It found that forcing humans to add special characters produces predictable patterns (Password1!) that barely help. NIST instead emphasizes length, a minimum of 15 characters when a password is the only factor, screening against breached-password lists, and allowing all printable ASCII and Unicode. Including special characters in a random generator does not contradict NIST—NIST objects to mandating them for human-chosen passwords, not to a generator using a wide character set.

Do special characters or length matter more?

Length matters more. Adding one character to the length multiplies the search space by the full pool size, while switching from 62 to 94 characters only raises entropy per character from about 5.95 to 6.55 bits. A 20-character lowercase password is far stronger than a 12-character password with all four character types. The right move is to maximize both: 16+ characters AND special characters, which a generator gives you at no usability cost because a password manager stores it.

What special characters are safe to use in passwords?

The widely supported set is !@#$%^&*()_+-=[]{}|;:',.<>?/. Nearly every modern service accepts these. Rare or non-ASCII symbols can trip encoding bugs on older systems, so most generators stick to standard ASCII punctuation for maximum compatibility. If a site rejects a symbol, it usually fails the moment you try to set the password, and you can regenerate without that character.

Why do some websites not allow special characters in passwords?

Almost always legacy or misconfiguration—old input filters, SQL-injection fears handled the wrong way, or outdated policy docs. NIST explicitly says all printable characters should be accepted, so a modern service has no good reason to block them. If you hit a block, try a longer password with only the allowed characters to compensate, and treat the restriction as a mild warning sign about that service's security hygiene.

Are special characters enough to make a password strong?

No. A short password with symbols (P@ss1!) is still weak because it is short and pattern-based. Strength comes from total entropy, which is length multiplied by the bits per character. Special characters help only when the password is also long and truly random. This is exactly why a generator plus a password manager beats a clever human-chosen password.

Do special characters protect against dictionary attacks?

They help, but only when randomly placed. Dictionary and rainbow-table attacks target human patterns—words, dates, and predictable substitutions like a trailing exclamation point. Randomly interleaved special characters push a password outside those precomputed sets and force pure brute force. A predictable pattern (word + '!') does not, because attackers already model that transformation.

Should I turn off special characters if a system rejects them?

Only for that specific system, and compensate with extra length. If a service caps you at letters and digits, generate a longer password (20+ characters) so total entropy stays high. Keep special characters on everywhere else. Never lower your default just because one legacy system is picky.

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