Calculate inboxes, domains, ramp schedule and cost for your cold email volume. Free warmup planner.
Daily target in; the fleet out — inboxes, domains, ramp, projections and true cost.
Lower stack cost. Back in the inbox. Built to send at any scale.
We rebuild it properly: secondary domains, inboxes, SPF, DKIM and DMARC set to enforcement, warmup and safe sending limits, blacklist monitoring on top. Send-ready in about 17 days. No campaigns, no copy, no lead lists. Infrastructure only.
Almost a decade building cold outreach infrastructure, including his own sending and verification stack built from scratch. 20+ B2B clients at companies worth $10M and above, all in tier one countries.
Free · Written plan + fixed price · No sales call required
Enter the number of cold emails you want to send per day at full volume. The calculator works backwards from that target: how many inboxes you need, how many domains those inboxes should sit on, the week by week ramp to get there safely, and what the stack costs per month. Run it before you buy domains or inboxes, not after. Most sending problems we see start with a plan that bought the wrong amount of infrastructure.
A brand new inbox has no sending history, so providers watch it closely. Warmup builds that history gradually: low volume at first, real looking exchanges, replies, and a slow climb toward your target daily volume. The ramp in your result is the safe version of that climb. Week one is deliberately boring. The jump in volume between weeks matters more than the total: a sudden spike from 5 to 50 emails a day is the pattern filters are trained to catch, while a steady ramp reads as a normal business mailbox getting busier.
Warmup is not a magic shield. It builds a basic reputation floor, and after that your list quality, your authentication and your copy decide where you land. Treat the ramp as the minimum, not a guarantee.
The math is simple once you fix one number: how many cold emails one inbox may send per day once it is fully warmed. Push that number too high and every inbox on the domain suffers together. Your result spreads the target volume across enough inboxes to keep each one in the safe zone, then groups those inboxes onto secondary domains so your main domain never sends cold outreach at all. If one secondary domain gets burned, you replace it and keep sending. That separation is the whole point of the setup, and it is why the calculator asks about domains separately from inboxes.
Warmup does not fix a bad list. It does not fix missing SPF, DKIM and DMARC records. It does not fix copy that reads like a spam template, and it does not rescue a domain that is already blacklisted. Check the foundations first with the Domain Health Checker and the Email Spam Checker, then warm up on top of a clean base. If you are starting from zero, the Secondary Domain Finder helps you pick sending domains that match your main brand.
We ran this calculator with a target of 1,000 emails per day. The other inputs were the defaults shown on the page: an inbox cost of $2.80 per month, a send cap of 40 emails per inbox per day, 3 inboxes per domain, and an expected reply rate of 4%.
The calculator returned 25 inboxes and 9 domains. It gave a warmup period of 7d and projected 1,200 replies per month. The ramp table showed Week 1 as Full, at 40 per inbox and 1,000 per day for the fleet, with status warm. On cost, it showed infrastructure at $72 per month, retail at about $190, and a 62% saving.
An operator uses that result before buying anything. Buy and set up the 25 inboxes across the 9 domains first, warm them for the period shown, and only then send at the full daily target.
Plan on at least 2 to 3 weeks of warmup before the first real campaign, following a gradual ramp. The calculator's schedule shows the week by week volumes. Sending full volume from a fresh inbox in week one is the fastest way to get it flagged.
Keep each inbox conservative even when it is fully warmed. Your sending target should be spread across inboxes, which is exactly what this calculator works out. Volume per inbox is a safety decision, not a bragging right.
An old domain with real sending history needs less ramp than a fresh one, but inboxes created today on that domain are still new mailboxes. Warm the new inboxes, and never send cold outreach from your main domain in the first place.
Yes. Keep warmup activity running alongside real sending so the inbox keeps a natural mix of exchanges. Stopping warmup the day campaigns start is a common and avoidable mistake.
No. Warmup builds reputation on a clean or neutral domain. If the domain is blacklisted or burned, fix the listing problem first or replace the domain. Warming a burned domain usually wastes weeks.
Only a few per domain. Spreading inboxes across several secondary domains limits the damage when one domain gets flagged, and it keeps each domain's total volume believable.
No. Warmup is one input into reputation. Placement also depends on authentication, list quality, engagement and copy. A warmed inbox sending to a scraped, unverified list will still land in spam.
Expect fast throttling, spam folder placement and possibly a suspended mailbox. Providers have no history to trust, so they treat sudden bulk sending as hostile until proven otherwise.
No tool can honestly guarantee that. Warmup done properly gives you a fair chance; the rest is list quality, authentication and what you actually send.
It covers what is broken, what we would build, the timeline, and one fixed price. Want it walked through instead? Book a 15 minute plan walkthrough.
Or just reply to the plan email. Either works.
