Author: Joe Maule, CFA
March 25, 2026
If you have been part of a startup for any length of time, you have heard the word "runway" tossed around in board meetings, investor calls, and hallway conversations. It is one of the most important numbers in your business. Yet in my experience, it is also one of the most frequently miscalculated, poorly communicated, and underutilized metrics in the startup world.
Runway shapes hiring decisions, product roadmaps, fundraising timelines, and whether your company survives long enough to find its footing. This post will walk you through how to calculate runway accurately, how to present it to investors and your board, and how to extend it when the numbers are not where you need them to be.
Runway is the number of months your company can continue operating before it runs out of cash. That is it. No revenue projections baked in, no hoped-for deals closing, no fundraise assumed. Just the cold math of how long your current cash will last at your current rate of spending.
Why does this matter so much? Because roughly 38 percent of startups fail due to cash flow problems. Not because the product was bad. Not because the team was weak. They simply ran out of money. Runway is your early warning system against that outcome.
The core formula is straightforward:
Runway (in months) = Current Cash Balance / Monthly Net Burn Rate
Let me break each piece down.
This is the actual cash sitting in your bank accounts right now. Not accounts receivable. Not the revenue you expect next quarter. Not the convertible note a friend "promised" to wire. Real, available, spendable cash. If you carry a balance on corporate credit cards or have payroll taxes due, subtract those amounts first. The number you want is what you could actually use tomorrow if you had to.
Your net burn rate is how much cash leaves the business each month after accounting for cash that comes in. The formula is simple:
Net Burn Rate = Total Monthly Cash Out − Total Monthly Cash In
For example, if your company spends $170,000 per month and brings in $25,000 in revenue, your net burn rate is $145,000 per month.
A couple of important notes here. First, use actual cash movement, not accounting accruals. Depreciation does not leave your bank account, so leave it out. An invoice you sent but have not collected on is not cash in hand, so leave that out too. Second, average your burn rate over at least three months, and ideally six. A single month can be misleading. Maybe you had a one-time legal bill, or a big customer paid early. Averaging smooths out those anomalies and gives you a more honest picture.
Suppose you have $1,000,000 in the bank and your three-month average net burn rate is $145,000 per month.
Runway = $1,000,000 / $145,000 = approximately 6.9 months
That means, all else being equal, you have about seven months before your cash hits zero. Mark the date on your calendar. That date should inform every significant decision you make.
The formula above is a useful snapshot, but it has a major limitation: it assumes nothing changes. In a startup, everything changes. Expenses tend to grow as you hire, expand infrastructure, and invest in go-to-market efforts. Revenue may grow too, but it often grows more slowly than founders expect.
A more conservative and, frankly, more useful approach is what some call a "no growth" runway calculation. You assume your expenses will continue to increase at their current pace, but your revenue stays flat. This gives you a worst-case planning number, which is exactly what you want when making decisions about cash.
For example, if your expenses are growing by $10,000 per month but revenue is steady, that $1,000,000 in the bank does not last seven months. It lasts closer to six. That one-month difference could be the margin between a strong fundraising position and a desperate one.
The best practice is to model three scenarios:
Running all three gives you a range, not a single number. And a range is far more useful for real decision-making. If you want a deeper look at how to build these scenarios in a full financial model, see How to Build a Financial Model from Scratch for Startups.
Knowing your runway is step one. Communicating it effectively is step two, and it is just as important. Investors and board members do not want to dig through spreadsheets. They want to understand your financial position quickly and trust that you understand it deeply.
Here is how to present runway well.
Open with a clear statement: "We have 14 months of runway at our current burn rate, based on $2.1 million in cash and a trailing three-month average net burn of $150,000 per month." That single sentence tells them the answer and the inputs. If they want to dig deeper, they can, but you have established credibility in ten seconds.
A single runway number is helpful. A chart showing how your runway has changed over the past six to twelve months is much more powerful. Is it growing because your revenue is ramping? Shrinking because you just made several hires? Stable because spending and revenue are moving in lockstep? The trend tells a story that a single number cannot.
Investors do not just want to know how many months you have. They want to know what you will accomplish in that time. Frame your runway around specific goals: "With 14 months of runway, we plan to reach $100K in monthly recurring revenue, close our first enterprise deal, and be in a strong position to raise our Series A." This transforms runway from a survival metric into a progress metric.
Lay out what your calculation assumes. Are you factoring in planned hires? A price increase? A big contract you are in late-stage negotiations on? Investors respect founders who are honest about the assumptions behind the numbers. They do not respect founders who present best-case projections as certainties.
Fundraising takes time. For seed-stage companies, plan for three to six months. For Series A and beyond, plan for four to nine months, sometimes longer. Your board should know not just when cash runs out, but when you need to start raising in order to close before things get tight. If you have 14 months of runway and expect fundraising to take six months, your trigger date is eight months from now. That clarity helps everyone plan.
This depends on your stage and the fundraising environment, but here are some general benchmarks.
After closing a funding round, aim for 18 to 24 months of runway. This gives you enough time to hit meaningful milestones before your next raise. In a tighter market, some advisors recommend targeting 24 to 36 months to give yourself extra cushion.
Start fundraising when you have 8 to 12 months of runway remaining. This gives you a buffer for the process to take longer than expected, which it almost always does.
If you are below 6 months of runway and not actively raising, treat it as a five-alarm fire. Your options narrow significantly at that point. Investors can sense desperation, and it weakens your negotiating position.
One more nuance: having too much runway is not always ideal either, particularly at very early stages. If you raised 36 months of runway but are not deploying that capital toward growth, it could signal to future investors that you are not being aggressive enough with the opportunity. Runway is not about hoarding cash. It is about having enough time to execute your plan while maintaining optionality.
If your runway is shorter than you would like, you have two fundamental levers: reduce what goes out or increase what comes in. Here are the most effective strategies I have seen work in practice.
Accelerate cash collection. If you bill monthly, explore offering a small discount for customers who switch to annual prepayment. One SaaS company shifted 30 percent of its customers from monthly to annual billing with a 15 percent discount and extended runway by nearly two months with no cost cuts at all. Cash today is worth more than slightly more cash spread over twelve months.
Convert pilots and trials to paid contracts. If you have prospects in free trials or unpaid pilots, create a clear, low-friction path to converting them. Even modest contract values add up when you have dozens of them.
Raise prices thoughtfully. Many startups underprice their product, especially early on. A 15 to 20 percent price increase, modeled carefully so you understand the churn risk, can meaningfully change your cash trajectory. But do the modeling first. A price increase that accelerates churn will make things worse, not better.
Focus on retention. Acquiring a new customer almost always costs more than keeping an existing one. Improving your retention rate by even a few percentage points can have a compounding effect on revenue over time, and it is often faster than building a new sales pipeline.
Audit your subscriptions and vendor contracts. This sounds basic, but it works. One practical tactic: cancel all corporate cards, reissue new ones, and let each team member migrate only the subscriptions they actually use. You will be surprised how many zombie tools are quietly draining cash every month.
Implement a hiring freeze on non-critical roles. People are almost always the biggest line item in a startup's budget. You do not necessarily need to lay anyone off, but pausing hiring for roles that are not directly tied to near-term revenue or product milestones can slow your burn rate significantly. Delay that second designer hire by a quarter. Push the office manager role to next year.
Renegotiate vendor agreements. If you have been with a vendor for a while, ask for better terms. Many vendors, especially software providers, will offer discounts or extended payment terms if you ask, particularly if the alternative is losing you as a customer.
Explore non-dilutive capital. Revenue-based financing, venture debt, and government grants can provide additional capital without giving up equity. These are not free money, and they come with their own trade-offs, but they can bridge a gap while you work toward stronger metrics for your next equity round.
Consider temporary compensation adjustments. Before resorting to layoffs, some companies offer across-the-board temporary salary reductions combined with additional equity. This is a sensitive conversation, but if done transparently and with a clear timeline for when compensation returns to normal, it can preserve your team while buying critical time.
Prioritize ruthlessly. The most underrated way to extend runway is to simply stop doing things that are not working. Kill the marketing channel with a terrible return on ad spend. Shelve the feature that three customers asked for but nobody will pay more for. Focus your team and your capital on the one or two things that will move the needle most in the next six months.
The best founders I have worked with think of runway as a resource to be managed strategically, the same way they manage their product roadmap or their hiring plan. Every dollar spent should be traceable to a specific outcome. Every month of runway consumed should correspond to measurable progress.
When you manage runway this way, something interesting happens in investor conversations. Instead of asking "how much runway do you have left?" investors start asking "what have you accomplished with the capital you deployed?" And that is a much better question to answer.
Runway is about more than survival. It is about buying yourself the time to build something that lasts. Know your number. Communicate it clearly. Manage it intentionally. And if the numbers are not where you want them to be, act early and act decisively.
The startup graveyard is full of companies with great products that simply ran out of time. Do not let yours be one of them.
This post is for informational purposes only and does not constitute financial advice. Consult with qualified professionals for guidance specific to your situation.
Joe Maule is a CFA charterholder and MBA graduate of Chicago Booth, currently leading Strategic Finance and FP&A at Nutrisense. He writes about finance, strategy, and technology.
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