The phone verification code, done right
The little 6-digit code at the center of verification looks trivial, but the small choices around it — length, expiry, wording, autofill — quietly decide whether users breeze through or give up.
Why six digits
Six digits is the sweet spot: one-in-a-million odds, plus an attempt lockout, is plenty secure, while staying short enough to read and type. Longer codes add friction without meaningfully more safety once you rate-limit.
Expiry and single-use
Keep the window short (a few minutes), allow the code once, and store only a hashed copy. A code that lingers for an hour is a code an attacker has an hour to use.
Make it effortless: autofill
The biggest completion win is not making people type at all. iBlueText formats codes so iPhones offer a one-tap suggestion and Android Chrome can auto-fill them with zero taps.
Wording that converts
Lead with the code, add a short "expires in 5 minutes," and a brief "don't share this code" note. Skip the marketing — this is a moment of intent, not a place to upsell.
Related
Frequently asked questions
How long should a verification code be?
Six digits is standard and ideal when paired with an attempt lockout — secure and easy to enter.
Should verification codes expire?
Yes — a few minutes. Short expiry plus single use limits an attacker's window.