Skip to content
ENExplore Calculators

Password Ageing Policy Calculator

Work out password ageing policy instantly with clear inputs, formula shown and shareable results.

About Password Ageing Policy Calculator

chage controls minimum and maximum password age plus a warning period. Modern guidance has reversed on rotation: NIST SP 800-63B advises against arbitrary periodic expiry because it drives predictable increment patterns and weaker passwords, recommending instead long passphrases, breach-list screening and forced change only on evidence of compromise.

Formula

Rotation load

changes per user per year = 365.25 / PASS_MAX_DAYS; fleet changes = users x that; tickets ~ 6 percent of changes

Worked example

With the default values below, Password Ageing Policy Calculator returns Password changes per user per year of 4.06. Change any input above and every figure here is recalculated in your browser.

Inputs used

PASS_MAX_DAYSaccepts 1–3,650 days
90 days
PASS_MIN_DAYSaccepts 0–365 days
1 days
PASS_WARN_AGEaccepts 0–90 days
7 days
Users affectedminimum 1
800

Results

Password changes per user per year
4.06
Password changes across the fleet
3,247
Estimated reset tickets per year
195
Current guidance
Frequent rotation increases predictable password patterns; NIST SP 800-63B now advises against arbitrary expiry

Step by step

  1. 1Values used
  2. 2Rotation load
  3. 3Password changes per user per year= 4.06
  4. 4Password changes across the fleet= 3,247
  5. 5Estimated reset tickets per year= 195
  6. 6Current guidance= Frequent rotation increases predictable password patterns; NIST SP 800-63B now advises against arbitrary expiry

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does NIST advise against forced rotation?

Because users respond with predictable transformations such as appending an incrementing digit, which weakens rather than strengthens the credential while adding support cost.

What is PASS_MIN_DAYS for?

It stops a user cycling through several changes immediately to return to their old password. It only matters when a password history is enforced.

Related Calculators

Password Ageing Policy Calculator | Calcrivo