How often should you clean your email list? A calculator for your own list
In short: From list size, monthly signups, a decay rate and the bounce share you want to stay under: the longest safe interval between cleans, whether to clean before each send instead, and the checks a month it needs. Limit: The preset rates model job changes from US tenure data; they aren't measured bounce rates, and they don't describe consumer lists.
Clean an email list often enough that the addresses gone bad since the last clean stay under your bounce target. At a yearly decay rate r and a target share b, that's every 12 × ln(1 − b) ÷ ln(1 − r) months. Enter your list size, signups, audience and target to get the interval and the checks a month it takes.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. See pricing
Checked as they arrive.
Modelled from BLS median job tenure for work addresses.
Type a rate you measured to override the model.
Filled from the platform's first published bounce line; lower it for a margin.
0.25 for quarterly; 0 if you rarely send.
Re-verify the whole list every 6 weeks.
- Longest safe interval
- 1.4 months
- Stale before each clean
- 1.9%
- Checks a month
- 9,167
- Checks a year
- 110,004
At 15.6% a year, the stale share reaches 2% after 12 × ln(1 − 0.02) ÷ ln(1 − 0.156) = 1.43 months; Brevo publishes 2% (campaigns or account can be suspended). Re-verifying 12,000 contacts on that schedule plus 500 new ones a month is about 9,167 checks a month.
| Stay under | Clean | Checks a month |
|---|---|---|
| 0.5% | Every 1 week | 52,500 |
| 1% | Every 3 weeks | 17,833 |
| 2% | Every 6 weeks | 9,167 |
| 5% | Every 15 weeks (about 3.5 months) | 3,967 |
The rate is a model of people changing employer, not a measured bounce rate, and not every stale address bounces at once. Measure your own with a re-verified sample in the decay calculator.
Next step
About 9,167 checks a month keeps this list under 2%.
That's a monthly job, so a monthly plan fits it: Pro ($39/month) covers 9,167 a month, fair use: 100,000 a month at full speed, then slower, never cut off. Start with the free checks on your own list.
No list right now? This tool stays free, no account, so bookmark it for next time. Ctrl+D (⌘+D on a Mac)
Ready to verify now? See Pro
Sample result
At 15.6% decay a year and a 2% target, re-verify the whole list every 6 weeks.
- Clean every
- 6 weeks
- Checks a month
- 9,167
- Stale at each clean
- 1.9%
What this means for you
12,000 contacts plus 500 new a month is about 9,167 checks a month: a monthly job.
- Interval from your target
- Before each send if rarer
- Checks a month and a year
- Platform bounce lines
- Cadence
- Decay
- Re-verify
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How do I work out how often to clean my email list?
- Enter the contacts on the list and how many new ones arrive each month. New contacts are counted as checked on arrival.
- Pick the audience closest to yours for the decay rate, or type a rate you measured on your own list.
- Set the stale share to stay under. Picking your sending platform fills in its first published bounce line.
- Enter how many campaigns a month go to the whole list, then read the interval, the checks a month and the table for other targets.
Example
- You enter
- 12,000 contacts, 500 new a month, all-workers rate (15.6% a year), Brevo's 2% line as the target, 4 campaigns a month.
- You get
- Re-verify the whole list every 6 weeks: the stale share reaches 2% after 1.43 months, and is 1.9% at each clean on a 6-week cycle. That's about 9,167 checks a month, 110,004 a year, with the plan that covers it named.
- Limits
- Runs in your browser.
How often should you clean your email list?
Often enough that the share gone bad since the last clean never reaches your bounce target, and before any send to a part of the list you haven't checked in months. Decay compounds: after t months at a yearly rate r, the stale share is 1 − (1 − r)^(t ÷ 12). Set that equal to the target b and solve for t, and you get the longest safe interval: t = 12 × ln(1 − b) ÷ ln(1 − r). At the all-workers model rate of 15.6% a year and a 2% target, that's about 1.4 months, so roughly every 6 weeks.
The common "clean it quarterly" advice works out at about 4.1% stale between cleans at the same rate, which is over Brevo's 2% line and close to HubSpot's 5% (bounce rate thresholds by platform). Our re-verification cadence guide covers triggers as well as the calendar: verify at entry, after a bounce spike, and before mailing anything that hasn't been checked recently.
What if I send less often than that?
Then clean before each send. If you mail the list every three months and the safe interval is six weeks, the list goes untouched for longer than six weeks every time, so the clean belongs right before the campaign. The calculator switches to that mode automatically and counts one clean per send. If you send weekly, every send between cleans carries some stale share, which is why the interval is set by the target, not by the send schedule.
How many verification checks a month does that take?
The list size divided by the interval in months, plus the new contacts you check as they arrive. A 12,000-contact list cleaned every 6 weeks with 500 signups a month is about 9,200 checks a month. That number is what to compare plans on: a monthly plan that covers it is cheaper than buying packs every clean. The rate comes from BLS median job tenure by role, a model for work addresses; enter your own rate from a re-verified sample if you have one, using the decay calculator.
How does the interval change with the target?
At the all-workers model rate of 15.6% a year:
| Stale share to stay under | Longest interval | In weeks |
|---|---|---|
| 0.5% | 0.35 months | 1 |
| 1% | 0.71 months | 3 |
| 2% | 1.43 months | 6 |
| 5% | 3.63 months | 15 |
In a spreadsheet: =12*LN(1-B2)/LN(1-A2) with the yearly rate in A2 and the target in B2, both as decimals.
Who uses this tool, and for what?
- Newsletter owners
- Replace a guessed "clean it now and then" with an interval tied to the bounce line of the platform they send on.
- B2B marketers
- Size a monthly verification volume for a CRM that adds leads every week.
- Agencies
- Put a re-verification schedule and its monthly check count into a client's retainer.
What can’t this tool tell you?
- The preset rates model job changes from US tenure data; they aren't measured bounce rates, and they don't describe consumer lists.
- It assumes decay is spread evenly through the year; a list from one event ages all at once.
- Not every stale address bounces at once, so the interval errs on the side of cleaning early.
Common questions
- How often should I clean my email list?
- Work it out from your decay rate and bounce target: at a 15.6% yearly rate and a 2% target, about every six weeks. If you send less often than that, clean before each send instead.
- Is cleaning my email list once a year enough?
- Not for a work-address list. At the all-workers model rate, a year is about 15.6% gone stale, far over every published bounce line.
- Do I need to clean a list I email every week?
- Yes, on the interval. Weekly sends remove hard bounces as they happen, but each bounce has already counted against you; re-verifying on schedule removes them before the send.
- What bounce rate should I aim for?
- Under your platform's lowest published line, with a margin: Brevo publishes 2%, HubSpot and Instantly 5%. Picking the platform fills the target in.
- Should new signups be verified as they arrive?
- Yes. Checking at entry keeps typos and fake addresses off the list, so the scheduled clean only has to catch decay.
Sources
The calculator makes the case better than we can.
Every per-address model above recurs each time you clean. A monthly plan with no per-email fees does not.
- Pro is never cut off: the first 100,000 emails a month run at full speed, then big lists run slower
- The email finder and enrichment included
- Published limits, so nothing is a surprise later
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.