Model the programme
How it works
Volume
Inboxes × sends per inbox × sending days. Keep sends per inbox at a level the domains can sustain — thirty is the ceiling I recommend.
Funnel
Each stage is a percentage of the previous one. Defaults are what good lists and good infrastructure produce; adjust to your own history.
Cost
Inboxes, domains at one per three inboxes, the sending tool, and whatever you pay for data and labour.
Break-even
The reply rate at which revenue equals cost. If it is close to your actual rate, the programme is fragile.
What the numbers are for
Most cold email decisions are made on send volume because it is the number everyone can see. It is the wrong number. Twenty inboxes sending 500 messages a day at a 0.6% reply rate produces fewer meetings than the same inboxes at 25 a day with a 3% rate, and the first fleet is burned inside a month while the second one runs for a year. This calculator puts meetings and cost per meeting in front of you so that the volume conversation becomes a quality conversation.
Defaults, and why they are conservative
A 2.5% reply rate assumes a well-built list and infrastructure that lands in the inbox. Below 1% almost always means one of those two is broken, not the copy. Thirty-five percent positive is realistic for B2B; it drops sharply on lists that were not qualified. Sixty percent of positives booking a meeting reflects a fast, low-friction booking process — a calendar link in the reply, not a three-email back-and-forth. Twenty percent close is a placeholder you should replace with your own figure.
Costs are what a Google Workspace fleet actually costs at scale: a few dollars per inbox, a dollar or so per domain per month amortised over the year, a mid-tier sending tool. Add data and labour if you want the true fully loaded number; set them to zero to see the infrastructure cost alone.
Reading the result
Cost per meeting is the figure to compare against alternatives — paid ads, SDR salary, an agency retainer. Under twenty dollars is normal for a well-run fleet, which is why cold email persists despite every announcement of its death.
Break-even reply rate is the diagnostic. If your actual reply rate is three times break-even the programme is robust and can absorb a bad month. If break-even is 2% and you are getting 2.4%, one deliverability incident puts you underwater; fix the fragility before adding volume.
Scaling the model
Doubling inboxes doubles cost linearly and, if the domains are properly warmed and the list holds up, roughly doubles meetings. Doubling sends per inbox does not: reply rates fall as per-inbox volume rises, because the mailboxes start looking like what they are. Run the calculator twice — once with more inboxes, once with more sends per inbox — and the meeting count will usually tell you which lever to pull. The capacity calculator sizes the fleet for a target meeting count from the other direction.
Frequently asked questions
What is a good cold email reply rate?
Two to four percent on a qualified list with warmed infrastructure. One to two is common and workable. Under one percent is a signal to stop and diagnose deliverability and list quality rather than scale.
How do I know my positive reply percentage?
Count replies from the last campaign and classify them: interested, not now, not interested, out of office, unsubscribe. Positive is the first group only. Most teams over-count by including polite declines.
Is cost per meeting the right metric?
It is the best single one for comparing channels. Pair it with meeting-to-deal conversion, because a channel that books cheap meetings with the wrong people is not cheap.
What does the labour figure cover?
List building, reply handling and data purchases — an hour a day plus a data subscription is typical for a fleet this size, which is where the $500 default comes from. Set it to zero to see infrastructure cost alone.
Does the model account for warmup?
No. It assumes the fleet is at full volume. New fleets spend the first three to four weeks below target, so the first month's output will be lower. The warmup calculator covers that period.
Can I use this for agency pricing?
Yes — set the deal value to what you charge per meeting or per client, and the cost inputs to what the infrastructure costs you. The margin per meeting falls out directly.
Last reviewed
What to run next
The checks that most often follow this one.
More in this category
Guides that go deeper
When the tools tell you something is wrong
The diagnostics here are free and always will be. When the fix is bigger than a DNS record, this is the work I do.
Deliverability rescue
Mail landing in spam, replies gone quiet, or a domain suddenly blocked. I find the actual cause rather than guessing, and fix it.
- Authentication and alignment failures
- Blocklist delistings and reputation repair
- Gateway and filter-level blocks
- A written report on what broke and why
Email & sending infrastructure
Sending domains, inboxes, authentication and warmup, built to survive volume instead of burning down in a month.
- Domain and inbox fleets at any scale
- SPF, DKIM, DMARC and tracking domains
- Google Workspace and Microsoft 365 inboxes
- Handover documentation you actually own
Domain, DNS & migration
Changing registrar, mail provider or host without a day of downtime or a week of mail silently failing.
- Registrar and nameserver moves
- Workspace and Microsoft 365 migrations
- MX, SSL and subdomain cutover
- Staged rollout with rollback at every step
Monitoring & retainer
Infrastructure drifts. Records get edited, certificates expire, domains get listed. Ongoing eyes on the fleet.
- Scheduled checks across every domain
- Alerts before your clients notice
- Monthly reporting
- Priority response when something breaks
Start with a call
Bring a domain and the symptom. I will tell you what is actually wrong and whether you need me at all — plenty of people leave that call able to fix it themselves.
Thirty minutes, no pitch
We will run the checks together on your actual domains, and you will leave knowing what is broken, what it takes to fix, and what it should cost. If that is a job you can do in-house, I will say so.