Startup Runway Calculator
Runway is one of the first numbers any founder learns to watch closely, because it answers the single most existential question a young company faces: how much time is left before the cash runs out. It's a deceptively simple calculation — current cash divided by monthly burn — but keeping it visible and current is what actually matters, since burn rate tends to change as a company hires, cuts costs, or grows revenue, and a runway figure calculated once at the start of the year can be dangerously out of date by the middle of it. This calculator takes your current cash balance and monthly burn rate (spending minus any revenue) to show exactly how many months of runway remain and the approximate date cash would run out at the current rate, giving founders and finance teams a clear, current number to plan fundraising timelines and spending decisions around.
How the Startup Runway formula works
A direct division, with an optional revenue offset:
Net burn = Monthly expenses − Monthly revenue Runway (months) = Current cash balance / Net burn Cash-out date = Today + Runway (months)
Step-by-step calculation
- Subtract monthly revenue from monthly expenses to find net burn — the actual amount of cash being spent each month after any income is factored in.
- Divide the current cash balance by net burn to find how many months of runway remain at the current rate.
- Add that number of months to today's date to estimate the approximate date cash would run out if nothing changes.
Worked example
A startup with $600,000 in the bank, spending $90,000/month and earning $15,000/month in revenue: Net burn = 90,000 − 15,000 = $75,000/month. Runway = 600,000 / 75,000 = 8 months — meaning, without a change in spending, revenue, or additional funding, the company would run out of cash in roughly 8 months.
Why runway should be tracked continuously, not calculated once and forgotten
The most common mistake founders make with runway isn't in the math — it's treating it as a one-time calculation rather than a number that needs recalculating as circumstances change. Burn rate rarely stays flat: hiring adds to monthly expenses immediately, while the resulting productivity or revenue gains typically show up with a lag. A single new senior hire, a new office lease, or a jump in marketing spend can meaningfully shorten runway overnight, while a strong sales month or a round of cost-cutting can extend it just as quickly. Most experienced operators recalculate runway monthly at minimum, and often weekly during periods of rapid change (right after a fundraise, during a hiring push, or when actively managing toward a cash-out date), rather than relying on a number calculated at the start of a quarter.
Runway also directly shapes fundraising timing in a way that's worth planning around deliberately rather than reactively. Raising a funding round typically takes several months from first investor conversations to money actually landing in the bank — commonly cited estimates range from 3 to 6 months for a typical process, sometimes longer in a tougher market. That means waiting until runway is down to 2 or 3 months before starting to raise puts a founder in a genuinely weak negotiating position, often forced to accept worse terms simply because the clock is visibly running out, or worse, running out of cash before a round closes at all. A common rule of thumb is to begin fundraising conversations with somewhere around 6 to 9 months of runway remaining, giving enough buffer for the process to play out without cash pressure distorting the negotiation.
It's also worth distinguishing gross burn (total monthly expenses) from net burn (expenses minus revenue), since both tell a slightly different story. Gross burn shows the full scale of spending regardless of how much revenue is offsetting it, which matters for understanding cost structure and where money is actually going. Net burn — what this calculator uses for the core runway figure — reflects the actual rate cash is depleting, which is the number that determines the real cash-out date. A company with high gross burn but strong, growing revenue can have a perfectly healthy net burn and long runway, while a company with modest gross burn but no revenue at all has a net burn equal to its gross burn — the same underlying spending can imply very different urgency depending on the revenue side of the equation.
Frequently asked questions
What's the difference between gross burn and net burn?
Gross burn is total monthly spending with no revenue offset. Net burn subtracts monthly revenue from that spending, reflecting the actual rate cash is depleting — net burn is what determines true runway, since revenue is offsetting some of the cash outflow.
How much runway should a startup try to maintain?
There's no universal number, but many experienced operators aim to start fundraising with at least 6 months of runway remaining, since a typical fundraising process can take 3-6 months from start to closed funding, and starting too late puts founders in a weaker negotiating position.
Does burn rate usually stay constant month to month?
Rarely — burn rate typically shifts as a company hires, changes vendor contracts, adjusts marketing spend, or grows revenue, which is why runway should be recalculated regularly with current numbers rather than relying on a figure from months earlier.
Should investor funding already committed but not yet received be included in the cash balance?
Generally no — runway calculations should reflect cash actually in the bank and available to spend, not funding that's expected or verbally committed but hasn't legally closed, since deals can fall through or be delayed.