Free tool · 100% in-browser
Deliverability calculator
Enter the numbers from your last send to get your delivery, bounce, spam-complaint, open and unsubscribe rates — each scored against the thresholds that matter (complaint rate under 0.3%, bounce under 2%). It quickly shows which metric is dragging your sending down. Calculated in your browser.
Deliverability FAQ
What's a good spam complaint rate?+
Keep it under 0.3%, and ideally under 0.1%. Gmail's Postmaster Tools and the 2026 bulk-sender rules treat 0.3% as the line where senders get throttled. Complaint rate is usually measured as spam reports divided by delivered messages.
How is bounce rate calculated?+
Bounces divided by emails sent. Under 2% is healthy; above 5% signals a list-quality problem that hurts reputation. Hard bounces (bad addresses) should be removed immediately; repeated soft bounces should be suppressed over time.
Should complaint rate use sent or delivered?+
Delivered is the more meaningful denominator, since a recipient can only complain about mail that reached them — that's what this calculator uses. Some dashboards use sent, which produces a slightly lower number. Either way, keep it well under 0.3%.
What delivery rate should I aim for?+
Above 98% delivered (accepted by the receiving server) is healthy. Note that 'delivered' means accepted, not necessarily inboxed — a message can be delivered to spam. Pair these metrics with seed-inbox testing to gauge actual placement.
Related: compliance checklist · emails going to spam