Your email bounce rate is the number of bounced emails divided by the number you sent, times 100. Under 2% is the common rule of thumb for a healthy list, and Amazon SES puts accounts under review when hard bounces reach 5%. Enter your numbers below to get your total, hard and soft bounce rates and how many bounces your next send can absorb.
Email bounce rate calculator
Healthy
| Total bounce rate (of sent) | 1.50% |
|---|---|
| Hard bounce rate | 0.80% |
| Soft bounce rate | 0.70% |
| Delivered | 4,925 (98.50%) |
| Bounce rate if your tool divides by delivered | 1.52% |
| Max bounces on next send to stay under 2% | 99 |
- Remove all 40 hard-bounced addresses before the next send.
Nothing you type is stored or sent anywhere. The calculator runs in your browser.
How to use the bounce rate calculator
Open the report for one campaign or one sending day in your email tool. Copy four numbers into the calculator: emails sent, hard bounces, soft bounces, and how many you plan to send next. The results update as you type.
If your tool only shows one bounce figure, put it in hard bounces and leave soft at zero. You will get a slightly pessimistic reading, which is the safe side to be on.
How it works: the email bounce rate formula
The calculator uses these formulas. You can check any result by hand.
- Total bounce rate = (hard bounces + soft bounces) / emails sent x 100
- Hard bounce rate = hard bounces / emails sent x 100
- Soft bounce rate = soft bounces / emails sent x 100
- Delivered = emails sent - hard bounces - soft bounces
- Bounce rate on a delivered basis = (hard + soft) / delivered x 100
- Bounce budget = the largest whole number of bounces that keeps the next send under 2%
Why show two versions? Most guides divide by emails sent. Some platforms, including Klaviyo's own glossary, divide by delivered emails, which gives a slightly higher number. If your dashboard and your own math disagree, this is usually why.
The split between hard and soft follows the mail server's status code. RFC 3463, the standard for these codes, defines 5.x.x codes as permanent failures that are "not likely to be resolved by resending the message", and 4.x.x codes as temporary failures where "sending in the future may be successful". Code 5.1.1 means the mailbox does not exist. Code 4.2.2 means the mailbox is full.
The status bands come from two places. The 2% line is a widely used rule of thumb rather than a hard rule; Mailtrap's bounce rate guide calls anything below 2% normal and 2% to 5% a warning level. The 5% and 10% lines are official. Amazon SES says it places an account under review when its bounce rate reaches 5%, and may pause sending at 10%. SES counts only hard bounces for this, which is why the tool checks your hard bounce rate against those two lines.
Worked example
This is an example, not a benchmark. Say you sent a cold email campaign to 1,000 contacts. Your tool reports 60 hard bounces and 20 soft bounces.
- Total bounce rate: 80 / 1,000 x 100 = 8.00%
- Hard bounce rate: 60 / 1,000 x 100 = 6.00%
- Delivered: 1,000 - 80 = 920, which is 92.00%
- On a delivered basis: 80 / 920 x 100 = 8.70%
- Bounce budget for another 1,000 emails: 2% of 1,000 is 20, so at most 19 bounces keeps you under 2%
A 6.00% hard bounce rate is above the 5% level where Amazon SES starts a review. The list is the problem here. Remove the 60 dead addresses, verify the remaining 940, and do not send to the rest until that is done.
What is a good email bounce rate, and what to do next
Aim for a total under 2%, with hard bounces as close to zero as you can get. For opt-in newsletters that is very achievable, because people gave you their address. Cold email lists bounce more because the data ages: people change jobs and company domains change.
Hard bounces need action straight away. Every hard bounce is an address that does not exist, and sending to it again tells mailbox providers you do not look after your list. Most platforms remove them for you. Mailchimp, for example, cleans hard-bounced addresses immediately, and turns a soft bounce into a hard bounce after 7 soft bounces for a contact with no activity, or up to 15 for one with past activity.
If your rate is above 2%, work through these in order:
- Suppress every hard-bounced address.
- Verify the rest of the list before the next send. Our guide to finding missing emails and cleaning a contact list covers how.
- Check where the list came from. If you bought it, read the checks to run before buying a B2B email list.
- Check your sending setup. A broken SPF record can cause rejections that look like bounces; the SPF record builder checks yours.
- Read why cold emails go to spam if your bounces are low but replies are too.
Need contacts that do not bounce in the first place? Find customers has verified B2B lead lists and tools to fill in missing emails.
FAQ
How do you calculate email bounce rate?
Divide the number of bounced emails by the number of emails sent, then multiply by 100. For example, 75 bounces from 5,000 sent is 75 / 5,000 x 100 = 1.50%. Some platforms divide by delivered emails instead, which gives a slightly higher figure. The calculator above shows both, plus separate hard and soft bounce rates.
What is a good email bounce rate?
Under 2% is the common rule of thumb, and Mailtrap's guide treats 2% to 5% as a warning level. Hard bounces should be as close to zero as possible. Amazon SES places accounts under review when the hard bounce rate reaches 5% and may pause sending at 10%, so treat those as limits you never want to see.
What is the difference between a hard bounce and a soft bounce?
A hard bounce is a permanent failure, usually because the address does not exist. Mail servers return a 5.x.x code, such as 5.1.1. A soft bounce is temporary, such as a full mailbox or a busy server, and returns a 4.x.x code. Remove hard bounces straight away. Soft bounces can be retried, but suppress addresses that keep failing.
Why is my cold email bounce rate so high?
Usually because the list is old or was never verified. B2B data goes stale as people change jobs and companies change domains. Guessed address patterns also bounce often. Verify every address before sending, remove hard bounces after each send, and keep each send small until your bounce rate is back under 2%.
Do soft bounces count toward the bounce rate?
In most email tools, yes: the total bounce rate includes both. Amazon SES is an exception for its account review, which it bases on hard bounces only. That is why this calculator shows hard, soft and total rates separately, so you can compare against whichever rule your sending platform uses.
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