Why Some Verification Codes Are 4 Digits and Others 6

Code length is a trade-off: 4 digits are quick to type, 6 or more are much harder to guess. Apps add limits on attempts so even short codes stay safe.

The numbers behind it

A 6-digit code is 100 times harder to guess than a 4-digit one. That matters most for sign-ins, so most large apps use 6 digits.

Why short codes are still safe

Apps let you try only a few times before blocking further guesses, and the code expires within minutes. With 5 tries at a 4-digit code, the chance of a lucky guess is 1 in 2,000.

When you see each length

• 4 digits: low-risk confirmations, some delivery and ride apps.
• 6 digits: most sign-in and two-step codes, and authenticator apps.
• Letters and digits: some services, such as Google, add a prefix like "G-" so you know who sent it.

"Enter the 4-digit code"

If a screen asks for 4 digits but your text shows more, you may be looking at a different message. Check the sender and use the newest code.

Codes that are links instead

Some services send a magic link rather than a number: you tap it and you are signed in. Links are easier on the same device but awkward when you sign in on a computer and the email lands on your phone. Many apps now offer both, so if a link opens in the wrong place, look for a code in the same message or ask for a code instead.

FAQ

Is a 4-digit code less secure?

A little, which is why apps limit attempts and expire codes quickly.

Why do some codes include letters?

A prefix such as G- shows which service sent it and helps you spot fake requests.

Can I choose the code length?

No. Each app decides.

Related: what an OTP is · how long codes last · Google security code texts.