Startup Runway and Burn Rate Calculator

Runway is the number of months a company can keep operating before its bank balance reaches zero, assuming its spending and income continue at the rate you specify. The basic formula could hardly be shorter: divide the cash you have by the amount of cash you lose each month. A business holding $600,000 and losing $50,000 monthly has twelve months. The simplicity is the reason it is so widely used, and also the reason it is so easy to get wrong, because every word in that definition hides a judgment.

Take the word cash. It means money in the bank that you can actually spend, not revenue you have invoiced, not a signed contract and not money a lead investor has verbally promised. Take the word monthly. A figure drawn from one unusually quiet month or one month with an annual software prepayment will mislead you. And take the word continue, which assumes nothing changes, even though a growing startup is changing every week. A good runway estimate states each of these assumptions out loud.

For a founder, runway is better understood as a measure of decision time than a countdown. It tells you how many months you have to reach a milestone that makes the next financing possible, or to reach break-even so you no longer need one. A calculator turns the arithmetic into an instant answer, but the value comes from changing the inputs and discovering which decisions buy you the most additional months at the least cost to the business.

*Rounded for readability. Use the calculator above for exact month-by-month results.

Gross burn is the total amount of cash a company spends in a month: salaries, contractors, rent, software, cloud hosting, advertising, insurance, legal bills and everything else that leaves the account. It ignores any money coming in. Net burn subtracts cash receipts from customers, so it shows the real monthly drain on the bank balance. If you spend $158,000 and collect $42,000, gross burn is $158,000 and net burn is $116,000.

Runway is almost always calculated from net burn, since the question is how long your reserves will last given what you really lose. Gross burn still earns its place. It shows how large your cost base is, which indicates how much revenue you would need to break even, and it gives you a worst-case runway if revenue stopped suddenly. A company that depends on a single large customer should look at gross-burn runway at least occasionally, because that is the number that applies if the customer leaves.

A common error is mixing the two. A founder who divides cash by gross burn will understate runway if there is meaningful revenue, and one who divides by a hand-picked net burn that includes optimistic collections will overstate it. Write the definition next to the figure whenever you share it. Board decks and investor updates generally show net burn, with gross burn beside it, so readers can see both the cost structure and the actual cash drain without needing to ask.

The largest line for most startups is payroll, and the number to use is the fully loaded cost of each person, not their salary. Employer payroll taxes, health insurance, retirement contributions, equipment, software licences, and in some countries mandatory bonuses or statutory contributions all add to the base salary. A common rule of thumb is that loaded cost runs meaningfully above salary, but the true figure varies by country and benefits plan, so pull it from your payroll provider rather than guessing.

Next come the costs that are easy to forget because they do not arrive monthly. An annual software subscription paid in January, a legal retainer, quarterly estimated tax payments, an insurance premium, a trade-show deposit and a security audit are real cash outflows. If you only use last month's bank statement, a month without any of these will make burn look lower than it is. A more reliable approach is to average the trailing three to six months and then add known upcoming lump payments as separate items.

Be explicit about what you are excluding. Non-cash expenses such as stock-based compensation, depreciation and amortization appear in an income statement, but they do not reduce the bank balance and should not be in a runway model. Capital expenditures, debt repayments, founder loans and tax settlements do move cash even if they are not operating expenses, and many accountants leave them out of burn by default. Decide which of these you include, and keep the choice consistent from one month to the next.

Revenue and cash receipts are different things, and for runway only the second matters. A company that invoices customers on net-60 terms recognises revenue when it delivers, but it receives cash two months later. During rapid growth, that gap can be large, because each month's invoices are bigger than the payments arriving from earlier months. A startup can appear profitable on paper and still run out of cash, simply because customers pay more slowly than the company pays suppliers and staff.

Subscription businesses see the opposite pattern when customers prepay. If a customer pays $12,000 for an annual plan on the first day, the company receives all twelve months of cash immediately, yet accounting rules typically recognise revenue gradually over the year. The unrecognised portion sits on the balance sheet as deferred revenue. For runway, the cash is what counts, but a founder should remember that the service obligation continues, and that a spike of annual renewals in one quarter will flatter burn in that quarter without improving the underlying monthly trend.

To keep your model honest, use cash received in the bank for the revenue input, and review accounts receivable regularly. Note which customers are late and which represent a large share of your receipts. If one customer accounts for a quarter of collections, test the case where its payment slips by sixty days. For consumer businesses or marketplaces, also consider refunds, chargebacks and payment-processor holdbacks, which can delay or reduce the money that reaches the bank account.

Suppose a software company has $1,150,000 in cash. In a typical month it collects $42,000 from customers. Its spending is $118,000 on payroll, $17,000 on hosting and tools, $14,000 on marketing, and $9,000 on rent and other expenses, a total of $158,000. Gross burn is therefore $158,000, and net burn is $158,000 less $42,000, which is $116,000. Runway is $1,150,000 divided by $116,000, or approximately 9.9 months.

Now test a decision. The team plans to hire two engineers at a fully loaded cost of $14,000 per month each. That adds $28,000 to expenses and brings net burn to $144,000. Runway falls to $1,150,000 divided by $144,000, which is about 8.0 months. Two hires cost nearly two months of life, and the calculator makes that trade visible. If the hires are expected to ship a feature that unlocks enterprise customers, the cost may be worth it, but the decision is now an explicit one rather than an accident of hiring.

For contrast, look at the gross-burn runway: $1,150,000 divided by $158,000 is about 7.3 months. That is the answer if every customer left tomorrow, and it is a useful stress figure. The spread between 7.3 and 9.9 months shows how dependent the company is on its existing revenue. A founder who sees that spread can ask sensible questions: how reliable are the receipts, how long are the contracts, and what is the plan if one large customer churns?

The formula above assumes burn is constant, which is rarely true for a company that is growing. If revenue rises, net burn falls over time and the real runway is longer than the simple division suggests. If costs rise faster than revenue, the reverse happens. A more careful model projects each month separately, subtracts that month's net burn from the remaining balance, and finds the month in which the balance would turn negative.

Revisit the earlier company and suppose collections grow by $2,000 every month while expenses stay at $158,000. In month one net burn is $116,000, in month two it is $114,000, and so on. After ten months the cumulative burn is $1,070,000, leaving $80,000. Month eleven burns $96,000, so the remaining $80,000 lasts about 0.83 of that month. Runway is roughly 10.8 months rather than 9.9, an improvement of nearly a month from steady, modest revenue growth.

This works in the other direction too, and downside scenarios deserve at least as much attention as optimistic ones. Model the case where growth stalls at today's revenue, the case where one large customer leaves, and the case where hiring proceeds as planned but revenue lags by a quarter. A range of three scenarios is far more useful in a board discussion than one confident number. The point of the exercise is not to predict the future but to know which assumptions the company's survival depends on.

Calculating runway to a zero balance is mathematically correct, but practically misleading. No sensible company plans to hit zero on a specific day, since payroll cannot be missed, suppliers must be paid, and a financing that is late by a few weeks could be fatal. Many founders therefore define usable runway as the time until cash falls to a minimum buffer, such as three months of payroll or whatever amount lets them wind down the business responsibly if it comes to that.

Using the earlier example, if the company wants to keep $240,000 in reserve, its usable cash is $910,000, and runway at $116,000 net burn is about 7.8 months rather than 9.9. The gap of more than two months is the cushion that protects employees and customers if a financing falls through. The calculator makes this easy to test by adjusting the cash input downward, or by using a minimum-balance field if one is provided, so you can see both numbers side by side.

A related idea is what Paul Graham of Y Combinator described as being default alive or default dead. A company is default alive if, on its current growth and expense trajectory, it will reach profitability before it runs out of money without raising more. It is default dead if not. The runway calculator does not make that judgment for you, but projecting several months of revenue growth against costs is the first step toward answering that question honestly.

Raising money takes longer than most first-time founders expect. Preparing materials, meeting investors, handling follow-up diligence, negotiating terms and closing legal documents can take several months, and many processes take longer than planned. A common planning guideline is to begin when you still have somewhere between six and twelve months of runway, though the right figure depends on your stage, your network, and how the market is behaving at that time.

The reasoning is about negotiating position. An investor who learns that you have two months of cash left knows you cannot walk away, and the terms offered will reflect that. A company with ten months of runway can decline a poor offer, extend the process, or take a smaller amount from existing backers. In the earlier example, with 9.9 months at current burn and 8.0 months if two engineers join, the founders would want to begin the process almost immediately rather than wait for next quarter.

Work backward from the date your cash would reach your minimum balance. Subtract the expected duration of the raise, perhaps six months, and subtract a margin for delay. The result is the date by which materials and metrics should be ready. If that date is already past, the realistic choices narrow to reducing burn, seeking bridge financing from existing investors, or pursuing revenue that does not depend on a new round. A calculator gives you the starting point for that backward calculation.

Runway tells you how long you can last, and a burn multiple tells you how efficiently you are using the cash. The burn multiple, popularised by investor David Sacks, divides net burn over a period by net new annual recurring revenue added in the same period. A company that burns $1.2 million in a year while adding $600,000 of net new ARR has a burn multiple of 2.0. It is paying two dollars of burn for every dollar of new recurring revenue.

Lower is better, since it means each dollar of burn buys more growth. Commonly cited rough guides treat values below one as excellent, values between one and two as acceptable to good, and values above three as a warning sign, but those thresholds are heuristics from particular periods and business models, not rules. Early-stage companies with little revenue can have very high or undefined multiples. Use the metric as a conversation starter about whether spending is producing growth, not as a pass-fail grade.

Combining the two metrics gives a fuller picture. A company with twelve months of runway and a burn multiple of five is in a different position from one with twelve months of runway and a multiple of one. The first is likely to struggle at its next raise unless growth improves, while the second has demonstrated that capital converts into revenue. When you test scenarios in the calculator, ask whether a decision that extends runway also improves efficiency, or merely postpones the same problem.

There are only two ways to lengthen runway: add cash or reduce net burn. Adding cash can mean raising equity, taking venture debt, arranging a revenue-based financing facility, collecting receivables faster, negotiating annual prepayment from customers, or applying for grants and tax credits where available. Reducing net burn means cutting costs, raising prices, improving conversion or increasing collections. Each lever has a different speed, certainty and cost to the business, and the calculator helps you compare them in months gained.

Cost cuts have the fastest effect, but also the highest risk when they reduce the capacity that produces growth. Payroll is the biggest lever and the hardest to pull, because it affects people and morale. Consider first the lower-impact items: unused software seats, cloud over-provisioning, marketing channels with poor payback, and contractors on open-ended engagements. Renegotiating supplier terms and shifting from monthly to annual billing for customers can improve cash timing without reducing the product or the team.

Sequence matters. Making a modest cut early costs less than a drastic cut later, when options have narrowed and the market knows you are under pressure. Run the numbers for a plan that reduces burn by ten percent now against one that waits three months and then needs thirty percent. The earlier plan usually preserves more months and more optionality. The calculator cannot weigh the strategic consequences, but it can show you how quickly a delay erodes your choices.

Investors usually want to see runway alongside the figures that produced it: opening cash, net burn for the month, closing cash, and the assumption used for the forward projection. State whether the forward estimate uses the trailing three-month average burn or a budget, and whether the figure is calculated to zero or to a minimum balance. Consistent definitions month to month matter more than choosing the perfect one, since the trend is often more informative than any individual figure.

Be especially careful with currency and seasonality. A company paying staff in one currency while collecting revenue in another will see its burn move with exchange rates. A business with strong seasonal sales should avoid extrapolating a peak month into the future. If your revenue arrives mostly in a few months, use a twelve-month model rather than a single-month figure. Mention known one-off items so that an unusual month does not distort the headline estimate and prompt an unnecessary alarm.

Within the team, think carefully about how much to share. Employees who understand the company's financial position can make better decisions and are less likely to be alarmed by rumors, but a single number can be misunderstood without context. Pairing the runway figure with the plan to extend it, and with the milestones that will unlock the next financing, turns a frightening number into a shared goal. Update the model whenever a material hire, contract or expense changes the picture, and keep a dated record of earlier versions.