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Burn rate & runway calculatorHow many months of cash do you have?
Start with runway: enter what is in the bank, what comes in and what goes out each month. You get gross burn, net burn, months of runway and the month cash runs out, with the balance walked forward so growth counts.
Gross burn
$80.0k
cash out per month
Net burn
$58.0k
cash out minus cash in
Runway
21.3 months
cash runs out around Jul 2028
- Oct 2026$842.0k
- Nov 2026$785.1k
- Dec 2026$729.4k
- Jan 2027$674.8k
- Feb 2027$621.6k
- Mar 2027$569.6k
- Apr 2027$519.1k
- May 2027$470.1k
- Jun 2027$422.6k
- Jul 2027$376.7k
- Aug 2027$332.5k
- Sep 2027$290.2k
The workspace forecasts burn from payroll, hiring dates, churn and collection terms, and reads the real balance from your bank.
Runway first
Months of cash is the number that matters
Burn rate is the pace. Runway is how long you have at that pace. Founders raise, hire and cut against runway, not against a monthly spend figure alone.
A company with $80,000 of gross burn and $22,000 of collections has $58,000 of net burn. That is useful. The board question is still: how many months until the bank balance crosses zero? That is runway, and it is why this calculator walks the balance month by month instead of stopping at a single burn figure.
Treat runway as a line, not a slogan. Flat division (cash ÷ net burn) is fine when nothing changes. When revenue is growing, costs step up on hire dates, or a tax bill lands in one month, the honest answer is the month the balance actually hits the floor.
The formulas
How to calculate burn rate and runway
Three numbers, all from the bank, none from the P&L.
A worked example. A seed-stage company has $900,000 in the bank, collects $22,000 a month and pays out $80,000. Gross burn is $80,000; net burn is $58,000; flat runway is 900,000 ÷ 58,000 ≈ 15.5 months. If collections grow 5% a month and costs stay flat, the burn shrinks every month and the balance lasts about 21 months instead. That is the figure the calculator shows with its default inputs, and it is why runway should be walked along the curve rather than divided out.
Use a normal month. Annual insurance, a tax payment, a customer prepayment or a hiring bonus will make one month look nothing like the next; if the last three months differ a lot, average them, or model the lumpy items on the month they actually land.
What the widget misses
Hires the calculator understates
A static burn figure assumes this month's payroll is next month's payroll. Agreed start dates are not in the bank yet, and they shorten runway the day they land.
The inputs above are a snapshot: cash now, cash in, cash out. They do not know about an engineer starting in March, a seller in June, or employer taxes that rise with headcount. Those costs are real commitments; they just have not hit this month's burn yet. If you paste today's spend and ignore the roster, runway looks longer than the plan will allow.
- Start dates matter. A hire agreed for month four is invisible in month one's cash out, then permanently raises burn.
- Fully loaded cost. Salary is not the whole line: employer taxes, benefits and tools move with each role.
- One-offs and timing. A deposit, a tax bill or annual software renewals land in one month and make flat division lie.
That is why runway belongs next to a headcount plan and a cash flow forecast, not only in a calculator cell.
Reading the path
Default alive vs raise-dependent
Runway alone does not say whether you survive without another round. It says when cash runs out if nothing else changes.
Default alive (in the Paul Graham sense) means the current revenue and cost path can reach cash-flow break-even before the bank hits zero. You may still raise to grow faster; you do not need a round to keep operating.
Raise-dependent means the path still burns through cash before collections catch spend. The calculator can show a comfortable 18 months today and still leave you raise-dependent if planned hires and flat growth never close the gap. The fix is either more revenue, less burn, or a round sized to the milestone that makes the next path work.
Use the widget to know the month cash runs out on today's run rate. Use a full model to see whether growth, hiring and a planned raise change that month, and whether you are alive without one.
Reading the number
What a good runway looks like
The convention investors quote is 18 to 24 months after a round closes: enough time to reach the next milestone, then run a raise while there is still a year of cash to negotiate with. Under twelve months, the raise has to start now. Under six, most founders are choosing between a bridge and a cut.
Runway is only as honest as the burn it is divided by. The two things that quietly shorten it are hires that have been agreed but not yet paid (a start date three months out is not in this month's burn) and revenue that is booked but not collected. Both are why a runway figure belongs inside a forecast, not a spreadsheet cell.
- Recurring net burn strips out one-time revenue and one-off costs, so a single project payment does not make the company look healthier than it is.
- Runway on the curve counts the month cash actually crosses zero, so a tax bill in month eight lands in month eight.
- Cash from the bank. The balance the forecast starts from should be the real one, refreshed, not the number typed in at the last board meeting.
In the workspace
From a one-off calc to a connected forecast
The calculator above is arithmetic. The workspace computes burn and runway from payroll roles and their start dates, churn, collection terms, one-off costs and the balance it reads from your bank, and they move whenever any of those change.
Open Replafin, connect a bank or type an opening balance, add the roles you are paying and the ones you plan to hire, and the dashboard shows monthly burn and months of runway next to ending cash. Ask the assistant “what happens to runway if I delay the second engineer to March?” and it answers from the recomputed model. See the cash flow forecast guide for how the forecast is built, or start from a driver-based financial model so every statement stays linked.
Questions
Burn rate and runway, answered
What is burn rate?
Burn rate is how fast a company spends the cash it has. Gross burn is everything that leaves the bank in a month; net burn is that figure minus the cash that came in. A startup that is not yet profitable lives on net burn: it tells you how many months the money lasts.
How do you calculate burn rate?
Subtract cash collected from cash paid out in the same month to find net burn. Replafin's workspace calculates it from the cash flow forecast, so it changes with your figures and assumptions. Compare several months to account for one-off bills or customer prepayments.
How do you calculate runway?
Divide cash in the bank by net burn. $900,000 in the bank and $58,000 of net burn a month is about 15.5 months. If income is growing, walk the balance forward month by month instead of dividing, because the burn shrinks as you go. That is what the calculator above does.
How much runway should a startup have?
Common investor guidance is 18 to 24 months after a round closes, so there is time to hit the next milestone and run a raise before the money gets tight. Under six months is the point where most founders start a bridge or cut costs. Treat these as conventions, not rules.
What is the difference between burn rate and burn multiple?
Burn rate is cash spent per month. Burn multiple is net burn divided by net new ARR over the same period: how much you burn to add a dollar of recurring revenue. Under 1 is excellent, 1 to 2 is good for an early-stage company, and above 2 is expensive growth.
What does default alive mean for runway?
Default alive means the company can reach a cash-flow break-even without raising again, at the burn and revenue path it is already on. Default dead (or raise-dependent) means runway runs out before that path closes, so the next round or a cut is what keeps the lights on. The calculator shows when cash hits zero; a full forecast shows whether revenue catches burn before that month.
Know the month.Not just the number.
Model the next twelve months from real balances and see burn and runway move as the plan does. Starter is $200 a month; Pro is $500.