Plan for 24 to 30 months of runway after a seed round, and start raising the next round with at least 12 months of cash left. The gap between seed and Series A now runs past two years for most companies, and a fundraise takes six to nine months on its own, so a plan built on 18 months leaves almost no room for anything to go wrong.
That is the short answer. The rest of this piece is how to get to a runway number you can actually trust, and what to do with it.
Key takeaways
- Target 24 to 30 months of runway after a seed round, not 18.
- Start the next raise when you still have 12 months of cash, and treat 9 months as the latest safe start.
- Calculate runway from net burn that includes planned hires and committed spend, not from last month's bank statement.
- Set a decision date: the day you cut costs if the round has not started.
- Recompute runway every month after close and put it in front of your board.
Why the 18-month rule stopped working
For most of the last decade, founders were told to raise enough for 18 months. That advice assumed the next round would arrive roughly on schedule. The data says it does not.
Crunchbase reports that U.S. startups that raised a seed round of $1 million or more have taken more than two years to raise a Series A since 2023, and that the share of seed companies that go on to raise again has fallen sharply: 24% of the 2023 seed cohort and 16% of the 2024 cohort have progressed so far, against 55% or more for cohorts through 2020. Seed rounds also got bigger, with a median near $3 million, which makes it tempting to assume the money will last. It lasts only if the plan behind it is honest.
The money that is flowing is concentrated. In the third quarter of 2026, AI companies accounted for 82.7% of U.S. venture deal value through September, and only 81 first-time funds closed, the slowest pace in a decade. Globally, seed funding totaled $13 billion in Q3, with about 20% of it going to seed rounds of $100 million or more. Strip out those outliers and a typical seed company is competing for a smaller pool. The bank that works with more venture-backed companies than anyone describes it plainly: one of the most challenging fundraising environments in decades.
None of that means you cannot raise. It means the calendar is longer than the old rule assumed, and the plan has to absorb that.
How to calculate runway you can trust
Runway is cash divided by net burn. Both numbers are easy to get wrong in the founder's favor.
Use net burn, not gross burn, but only count revenue you have actually collected, not invoiced. Then make burn forward-looking. The burn that matters is next quarter's, including the hires you have already planned, the annual contracts that renew, and the payroll taxes that reset in January. A runway figure built from last month's spend is a figure for a company you are about to stop being.
Here is a worked example with illustrative numbers. Say a company closes a $3 million seed round and has $3.2 million in the bank. Current net burn is $95,000 a month, which suggests 33 months of runway. But the plan includes four hires over the next two quarters at a fully loaded $14,000 a month each, plus $8,000 a month of new software and contractor spend once the team is in place. Steady-state burn becomes $159,000 a month. Spread the hires over six months and the real runway is closer to 22 months, not 33. If revenue grows, that number improves. If the hires come in faster or a large customer pays late, it shrinks.
The gap between 33 and 22 is the most common runway mistake I see. Model hires on their actual start dates and fully loaded. Our runway and burn modeler and hiring plan calculator are built for exactly this.
The three dates every founder should know
Once burn is honest, turn runway into dates. Dates get acted on; months get rationalized.
- Zero-cash date. The month the bank balance hits zero at forward burn. Everything else is planned backward from here.
- Raise-start date. Twelve months before the zero-cash date. This is when you start conversations in earnest, with a data room and an updated model ready. Nine months before is the latest safe start, because a process that takes six months still leaves a little room.
- Decision date. If you have not started the raise by the raise-start date, or the first month of conversations is going badly, this is the day you cut burn to extend runway. Write down in advance what you would cut and in what order, so the decision is fast instead of agonizing.
Put all three dates in the monthly board update. When the board sees the same three dates every month, a slipping date becomes a conversation instead of a surprise.
What to do if you are under 12 months
Most companies that fail do not fail suddenly. SimpleClosure's H1 2026 shutdown report found the median time from last raise to closure was 2.28 years, and the median non-AI company had about $13,000 left when it closed. In other words, companies tend to run all the way to the end. CB Insights found that 70% of startups that shut down since 2023 cited running out of capital, which is usually the visible symptom of something earlier, like weak product-market fit or a raise that started too late.
If you are under 12 months, work the levers in this order:
- Cut the burn you control. Pause hires that have not started, renegotiate annual software, and move contractors to defined scopes. This is the fastest and cheapest runway there is.
- Pull revenue forward. Annual prepay with a modest discount, faster collections on open invoices, and pricing changes that existing customers will accept.
- Ask existing investors early. An insider bridge is far easier to arrange with nine months left than with three. If it comes as a SAFE or note, model the dilution before you agree to terms; the SAFE modeler shows what a cap actually costs at the next round.
- Be careful with debt. Venture debt can extend runway for a company with real revenue and a clear path to the next round. It makes a shorter runway worse if it comes with covenants you are likely to trip.
Bringing runway to the board
Runway belongs in every board update as three numbers: cash on hand, forward net burn, and the three dates. Add a downside case, typically revenue 20% below plan and hires on schedule, so the board sees how much margin the plan really has. Boards rarely punish a founder for a short runway they saw coming months earlier. They react badly to one they learn about late.
If you want a simple weekly habit that feeds this, the weekly number that tells you if you are actually okay is a good place to start.
The takeaway
Runway is not a fact about your bank account. It is a forecast about the future, and forecasts made by optimistic people run long. Plan for 24 to 30 months, calculate burn the way it will be rather than the way it is, turn the result into dates, and start the next raise with a year of cash left. The founders who do this rarely have to raise in a hurry, which is the best position to raise from.
Frequently asked questions
How many months of runway should a seed-stage startup have?
Plan for 24 to 30 months after a seed round. The median gap from seed to Series A now runs past two years, and the raise itself can take six to nine months, so 18 months leaves very little room for delays.
When should a startup start raising its next round?
Start in earnest when you still have about 12 months of cash, and treat 9 months as the latest safe start. Starting earlier gives you the option to walk away from bad terms.
Should runway be calculated with gross burn or net burn?
Use net burn, but count only revenue you have actually collected, and make it forward-looking. Include planned hires on their start dates, renewing contracts and committed spend, not just last month's expenses.
What should a founder do with less than 12 months of runway?
Cut the burn you control first, then pull revenue forward through prepayments and faster collections, then talk to existing investors about a bridge. Treat venture debt with care, because covenants can shorten runway instead of extending it.
Sources
- In Charts: Seed Deals Keep Getting Bigger As Odds Of Reaching Series A Fall Dramatically
- Crunchbase Data: Q3 2026 Posted A Record Count Of Billion-Dollar Rounds As The Global AI Race Heats Up
- Q3 2026 PitchBook-NVCA Venture Monitor
- State of the Markets Report H2 2026
- The H1 2026 Shutdown Report
- 400+ startup deaths