We'd plan on three or four senior engineers for a seed startup using AI tools. Size the team from what must ship before your next raise, plus one person who can review all of it, then price it. AI changes how much one engineer can carry, not how many people you need to own, review and cover the code. Add a fifth only against a named constraint.
For the wider set of decisions around a raise, see our startup scaling guides for engineering leaders.
How do I size my seed team?
What must ship before the next raise?
Write down the milestones the next round depends on and estimate each in engineer-months, using your own team's recent pace rather than a vendor's productivity claim. Add them up and divide by the months until you raise. Say the total is 12 engineer-months and the raise is four months away: that's three people doing the work, before anyone has reviewed a line.
Who can review everything that ships?
Our take: review is the limit, not typing. AI makes code cheaper to write and no cheaper to read, so the person who can judge a change becomes the scarce one. The rule we'd use is that every change gets read by someone who could have written it. With one engineer, nobody reads it. With two, each is the other's only reviewer and a day off stalls both.
What happens if one engineer leaves for a month?
Ask what ships, what breaks and who is on call if one person is gone for 30 days. If the answer is "nothing ships", you're one person short. Our 30-day plan if one engineer leaves shows what to have in place.
How many months of runway does each hire cost?
Divide your cash by the team's monthly bill. Every extra person shortens the answer, so price the headcount before you agree to it.
What does a 2, 3, 4 or 5 engineer seed team cost per month?
HighCircl's rate for senior engineers is €45-105/hr, and we'll assume 160 billable hours a month. One senior then costs 160 × €45-105 = €7,200-16,800. That rate is the whole bill, with HighCircl's 20% margin already inside it, so don't add it again. Swap in your own rate if you hire another way; the arithmetic is the same.
| Engineers | Monthly cost |
|---|---|
| 2 | €14,400-33,600 |
| 3 | €21,600-50,400 |
| 4 | €28,800-67,200 |
| 5 | €36,000-84,000 |
Take four seniors: €28,800 a month at the bottom of the band, €67,200 at the top. Where you land in the band moves the bill as much as a hire does, since the same four people cost more than twice as much at the top.
A fifth engineer adds one more of those monthly costs, which over six months comes to €43,200-100,800 of runway. That's the cost you'd have to justify.
Do AI seats replace an engineer?
No. Four paid seats at list prices of $10-125 per seat per month come to $40-500 a month, under 2% of a four-person bill even at the top seat price and the bottom rate. Our breakdown of what each AI coding tool costs per seat has the prices, checked in September 2026.
Usage-billed plans are the exception, since heavy agent use can add overage charges. Ask each vendor for a cap before you budget it.
Does AI mean a seed startup needs fewer engineers?
Not on the evidence. METR's 2025 study found experienced developers were 19% slower with AI tools, though they'd expected to be faster. Its 2026 update found speedups whose ranges include no speedup at all, and METR calls it "very weak evidence". METR expects the real 2026 figure to be higher. The 2025 study covered large, long-running repositories and the 2026 update included some greenfield work, but neither measures a seed team.
So there's no sourced multiplier to plug into a headcount plan. The "3 to 5 engineers" range you'll see online is one author's experience: andresmax.com's January 2026 post puts seed at three to five and cites no data. Use it as a sanity check on your own sizing, not as the target.
When to add the next engineer, and when to contract instead
Add a person when one of these is true:
- Your milestone estimate, at your measured pace, runs past your runway.
- Pull requests wait on one reviewer.
- A system has exactly one person who understands it.
"Competitors have six" isn't on the list.
Contract instead of hiring when the need has an end date: a launch, a migration before the raise, a security audit. You pay for the stretch you need and don't carry a permanent cost into a round that may not close. Hire when the role is an owner you'll want for years, such as the first backend lead.
What this means for your seed plan
Fix the team size as a range tied to the three triggers, not as a single number. Take the four-person bill to your board as a monthly range, and say which trigger would move you to five. That's a plan an investor can challenge on facts.
Keep AI seats as a small capped line with a usage alert, and don't let anyone cut a hire because of a productivity percentage nobody has measured at seed. If you're unsure about a role, contract it for a quarter and see whether the constraint disappears.
Your next budget is the Series A one: our Series A engineering budget runs the same arithmetic at twelve people.
Hiring senior engineers through HighCircl
If your plan needs seniors for a few quarters rather than a permanent team, a contract is the straightforward way to get them. HighCircl has no minimum hours, so you can stop when the work is done. A shortlist of three to five vetted candidates arrives in 72 hours, which matters when the raise date is fixed and waiting costs runway. See senior engineers through HighCircl.
FAQ
How many engineers do you need to raise a seed round?
No source sets a number. The ranges on ranking pages are opinion. Show investors what your team can ship before the next raise and who reviews it.
Can one engineer plus AI tools build an MVP?
Possibly, for a first version, but no study measures it. The 2025 METR study is about experienced developers on large existing codebases, and neither study measures a seed team building a new product. What a solo engineer lacks is a reviewer and cover, and AI tools don't supply either.
Should a seed team hire a junior developer?
Mostly no, and we cover the seniority question in detail in whether to hire a junior at seed. Review capacity is the reason: a junior adds code to read without adding anyone who can read it.
Do you need an engineering manager at seed?
Not at three to five engineers. A lead engineer or CTO who still writes code can run planning and review. Hire a manager when coordination, not code, is what slows the team.