Startup Cash Flow Runway Calculator – Know Your Burn Rate in 3 Simple Steps
Cash Flow Runway Calculator
Use this startup cash flow runway calculator to find your net burn rate and exactly how many months of cash your startup has left.
Use this free startup cash flow runway calculator to find out how many months your company can keep operating before the money runs out. Enter the cash in the bank, average monthly revenue and average monthly expenses, and the tool shows your net burn rate, gross burn and runway in months.
Quick answer
Runway = cash in the bank ÷ net monthly burn. Net burn = monthly expenses − monthly revenue. A startup with $600,000 in the bank, $25,000 of monthly revenue and $65,000 of monthly expenses burns $40,000 net a month and has 15 months of runway. Without that revenue, the same company would have only about 9.2 months.
Table of Contents
Running out of cash is one of the most common reasons startups fail, and it rarely happens by surprise to founders who track runway every month. Knowing your number tells you when to raise, when to cut costs and how hard to push for revenue.
This startup cash flow runway calculator gives you the answer in seconds. It runs in your browser, so your financials stay private.
What Is Cash Runway?
Cash runway is the number of months a business can survive at its current spending and income before its bank balance reaches zero. It assumes nothing changes, so it is a snapshot that founders, finance teams and investors use to judge urgency.
Burn Rate Explained
- Gross burn: total monthly operating expenses, such as salaries, rent, software and marketing.
- Net burn: gross burn minus monthly revenue, the amount your cash balance actually falls each month.
- Runway: cash balance divided by net burn.
Runway Formulas
- Net burn = average monthly expenses − average monthly revenue
- Runway (months) = cash in bank ÷ net burn
- Cash-out date = today + runway months
If revenue is higher than expenses, net burn is zero or negative, which means the business is cash-flow positive and runway is not limited by current operations.
How to Use the Startup Cash Flow Runway Calculator
Step 1: Enter Cash, Revenue and Expenses
Type your total cash reserves, your average monthly revenue (or 0 if you are pre-revenue) and your average monthly expenses. Use an average of the last three months to smooth out one-off spikes.
Step 2: Read Your Runway and Burn Rate
Press Calculate Runway. With $600,000 in the bank, $25,000 revenue and $65,000 expenses, the net burn is $40,000 a month and the runway is 15.0 months, flagged as a moderate runway that calls for planning the next funding round.
Step 3: Test a Pre-Revenue or Worst Case
Set revenue to zero to see the downside. The same company would burn the full $65,000 a month and have only 9.2 months left. Testing scenarios like a lost customer or a delayed launch shows how much buffer you really have.
How Much Runway Is Enough?
| Runway | What it usually means |
|---|---|
| Under 6 months | Urgent: cut costs or raise immediately |
| 6 to 12 months | Start fundraising now; rounds often take 3 to 6 months |
| 12 to 18 months | Healthy, but plan the next milestone and round |
| 18 to 24+ months | Comfortable; the range many investors like to see after a raise |
Runway Examples
| Cash | Revenue | Expenses | Net burn | Runway |
|---|---|---|---|---|
| $600,000 | $25,000 | $65,000 | $40,000 | 15.0 months |
| $600,000 | $0 | $65,000 | $65,000 | 9.2 months |
| $1,200,000 | $40,000 | $90,000 | $50,000 | 24.0 months |
| $250,000 | $10,000 | $35,000 | $25,000 | 10.0 months |
Ways to Extend Your Runway
- Review every recurring subscription and contract, and cancel what you no longer use.
- Delay non-essential hires until revenue or funding is secured.
- Negotiate longer payment terms with suppliers and shorter terms with customers.
- Offer annual plans with an upfront payment to bring cash in sooner.
- Focus marketing on the channels with the fastest payback.
- Explore grants, revenue-based financing or bridge funding.
Building a 12-Month Cash Forecast
Runway assumes today’s numbers stay flat, but real businesses change every month. A simple 12-month cash forecast adds planned hires, price changes, expected sales growth and big one-off costs month by month. Start with the figures you entered in the startup cash flow runway calculator, then adjust each month for known changes. The month where the balance first drops below zero is your real cash-out date.
Update the forecast at least once a month with actual results. Comparing plan against actual quickly shows whether costs are creeping up or sales are behind, which gives you time to react before runway gets short.
Default Alive or Default Dead?
A useful test is whether the company would reach profitability with the cash it already has, assuming current growth continues. If yes, it is often described as default alive. If not, it depends on raising more money. Knowing which side you are on helps you decide whether to focus on growth, cost control or fundraising first.
Want to know what the business could be worth? Try the Website Flipping Valuation Calculator. To grow revenue from existing traffic, use the CRO Calculator.
Frequently Asked Questions
How do I calculate startup runway?
Subtract monthly revenue from monthly expenses to get net burn, then divide your cash balance by net burn. The result is your runway in months.
What is the difference between gross burn and net burn?
Gross burn is total monthly spending. Net burn is spending minus revenue, which is how fast your cash actually goes down.
How many months of runway should a startup have?
Many founders aim for 18 to 24 months after raising money. Below 6 to 9 months, it is usually time to raise or cut costs.
What if my revenue is higher than my expenses?
Then you are cash-flow positive. Your runway is not limited by current operations, although big one-off costs can still reduce cash.
Should I use average or current monthly figures?
Averages over the last three months are more reliable, especially if spending or sales vary from month to month.
Is my financial data stored?
No. The startup cash flow runway calculator works entirely in your browser.