Cold email cost calculator: inboxes, domains, warmup and monthly cost

How the numbers are worked out

inboxes          = ceil(emails per day / sends per inbox per day)
domains          = ceil(inboxes / inboxes per domain)
emails a month   = emails per day x sending days
new prospects    = ceil(emails a month / emails per prospect)
monthly cost     = inboxes x mailbox price
                 + domains x yearly registration / 12
                 + the cheapest sequencer plan that covers your emails, contacts and inboxes
                 + verifying every new prospect's address
cost per 1,000   = monthly cost / (emails a month / 1,000)

Worked example (the defaults). 300 emails a day at 30 per inbox is 10 inboxes. At 3 inboxes per domain that is 4 domains. Over 22 sending days it is 6,600 emails a month, or 2,200 new prospects at 3 emails each. Instantly's Growth plan stops at 5,000 emails a month and Smartlead's Base plan at 6,000, so the calculator picks each vendor's next plan up. Plans change often; the table under the calculator shows the prices and limits it used, with the date each was read.

Time to full volume. New inboxes send warmup traffic only for the weeks you set (three by default), then start at 10 cold emails a day each and add 5 a week. At 30 per inbox you reach full volume in week 8. The ramp follows lemlist's published guidance (start at 10 to 15 a day, add about 5 a week, cap cold email at 25 to 30 and the total at 50 per mailbox); change it in "Ramp after warmup".

Why separate domains and many small inboxes

• Your main domain carries your real mail. Invoices, support replies and password resets come from it. If cold email damages its reputation, that mail suffers too. Cold email belongs on separate domains you can retire.
• Mailbox providers judge each inbox and domain by its history. A new inbox that sends hundreds of messages a day looks like a hijacked account. Volume comes from more inboxes at a modest rate each, spread across a few domains, so one problem does not take everything down.
• Every sending domain needs the full setup. SPF, DKIM and DMARC on each one, checked with the email setup checker. The sender rules guide explains why.

What staying legal and deliverable requires

The calculator prices the tools. These rules decide whether the mail is legal and whether it arrives:

• CAN-SPAM applies to business email too. Truthful headers and subject lines, a clear statement that the message is an ad, a valid postal address, and a working opt-out honored within 10 business days. Each violating email can cost up to $53,088. CAN-SPAM in plain English covers it in detail.
• Spam complaints have a hard ceiling. Gmail asks senders to stay under a 0.1% spam rate and acts at 0.3%. The calculator shows what that means in complaints per day at your volume.
• Unsubscribes must work fast. Yahoo requires bulk senders to honor them within 2 days, and Google recommends 48 hours.
• Addresses must be real and relevant. Verify each address before the first email; bounces hurt every inbox on the domain. Write to one person at one business for one relevant reason. Bought or scraped lists break the first rule and usually the law: automated address harvesting is an aggravated CAN-SPAM violation.
• Use tools that allow cold email. Transactional email services generally forbid it. Resend's acceptable use policy, for example, says: "You are prohibited from sending unsolicited messages of any kind, including cold outreach, purchased lists, or scraped contact data." (Resend)

What the calculator leaves out

• Where prospects come from. Lead databases and data tools are priced separately, and this site does not recommend bought lists.
• Writing, research and reply handling, which are most of the real cost.
• Taxes, and promotional prices (the price notes mention current promotions).
• Dedicated IPs, private warmup pools and other add-ons.

About the vendors in the table

The stacks are sorted by total price, nothing else. MailSetupCheck may earn a commission if you sign up for Instantly through this site; that does not change its position in the table, and the other vendors are listed and priced the same way. The affiliate disclosure lists every relationship.

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