Email Bounce Rate Explained: Formula and Benchmarks

TL;DR

Bounce rate = bounced emails divided by emails sent, as a percentage. Hard bounces are the ones that matter most for reputation.
Under 2% is the healthy target. Over 5% is where sending platforms start pausing campaigns.
Tools define it differently: Smartlead divides by total leads, not emails sent, so early rates look lower.
The fix is upstream: verify the list before you send.

The formula

bounce rate = (emails that bounced / emails sent) x 100. Send 1,000, 30 bounce: 3%. Always say which kind: hard bounces (permanent: the address doesn't exist) matter most; soft bounces (temporary: full mailbox, server down) mostly resolve themselves. See hard vs soft bounces.

What's a good bounce rate

Band	Reading
Under 2%	Healthy. Smartlead reports a median of about 1.5% across its senders (its own figure)
2-5%	Warning. Fix the list before the next send
Over 5%	Stop. Instantly auto-pauses campaigns above 5% once 200 emails are sent

Gmail's bulk-sender rules publish a spam-complaint threshold (under 0.3%) but no official bounce number, yet repeated sends to dead addresses still feed how your domain and IP are rated. See how many bounces burn a domain.

Why your tool and your ESP disagree

Instantly pauses a campaign when bounces exceed 5%, checked once at least 200 emails have been sent; the rule is on by default.
Smartlead auto-protection is off unless enabled, and its formula divides by the campaign's total leads rather than emails sent.
lemlist alerts at 10% and pauses at 50% after 100 leads.
Marketing platforms may count soft bounces differently or only after retries.

How to lower it

Verify every list before the first send, especially purchased, scraped and old lists. How.
Remove undeliverable and, for cold email, risky addresses.
Re-verify before follow-ups; lists decay. Decay rates.
Watch for small-sample noise: judge rates over a few hundred sends.

Calculate yours

Use the bounce rate calculator, which also shows each sending tool's threshold.

FAQ

What is a good email bounce rate?

Under 2% is the common target. Above 5% most sending platforms intervene.

How do you calculate email bounce rate?

Bounced emails divided by emails sent, times 100.

Does bounce rate include soft bounces?

Depends on the tool. Hard bounces are what damage reputation; check how your tool counts.

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Email	Verdict	Why
[email protected]	deliverable	Mailbox exists
[email protected]	risky	Shared inbox
[email protected]	risky	Accepts every address
[email protected]	undeliverable	Mailbox not found
[email protected]	undeliverable	Typo in the domain

Email bounce rate explained