# fail2ban bantime calculator

> Free fail2ban bantime calculator: convert values like 1d12h, 1w or 1mo to seconds, and see how long each repeat ban lasts with your bantime.increment settings.
>
> Source: https://fail2ban.dev/tools/bantime-calculator/ · Updated 2026-10-25 · Checked against fail2ban 1.1.1
> fail2ban.dev is an independent guide, not the official fail2ban project.

## How the calculator works

**The converter** is a port of fail2ban's own `str2seconds` parser, so it reads values exactly as fail2ban does: `1d12h`, `1h 30m`, `36h`, `1y-6mo`, plain seconds, and `-1` for a permanent ban. Watch out for `m` — it means minutes; a month is `mo`. The full list of units, common values and what `-1` and `0` mean is on the [bantime, findtime and maxretry](/config/bantime-findtime-maxretry/) page.

**The simulator** reproduces the code fail2ban 1.1.1 runs when `bantime.increment = true`:

- ban #1 is always the plain `bantime`;
- each later ban is `bantime × 2^n × bantime.factor` (or `bantime × factor × multiplier[n]` when you set `bantime.multipliers`);
- `bantime.maxtime` caps the result and `bantime.rndtime` adds up to that much random time;
- the last column shows how long fail2ban keeps the IP's record before it forgets it: 3 × the last ban length + `dbpurgeage`. An IP that returns after that starts again at ban #1.

Why the formula works this way, how `bantime.overalljails` counts bans across jails and which values to pick is explained in [incremental bans](/config/bantime-increment/). Copy the generated block into `jail.local`, or build a complete config with the [jail.local generator](/tools/jail-generator/).

## FAQ

### Why does ban #2 last four times the bantime with factor 2?

Because the default formula multiplies by both `2^n` and the factor: with `bantime = 1h` and `bantime.factor = 2`, ban #2 is 1h × 2 × 2 = 4h, ban #3 is 8h, ban #4 16h. Use `factor = 1` if you want plain doubling (1h, 2h, 4h…).

### Why does the simulator stop growing at a certain ban?

That's `bantime.maxtime`: no ban can be longer. Clear the field to see uncapped values — they grow quickly, so a cap of a week or a month is normal.

### Is 1mo exactly 30 days?

No. fail2ban defines a month as a year divided by 12, using 365.25-day years: 2,629,800 seconds, about 30.44 days. A year (`1y`) is 31,557,600 seconds.

### Why do my real bans not match the table?

Usually because the database forgot the IP: with the default `dbpurgeage = 1d` the record of a one-hour ban is deleted about a day after the ban, so the next ban counts as #1 again. A random `bantime.rndtime` also changes every ban slightly.