Startup Runway Calculator

What is a free startup runway calculator online?

A free startup runway calculator online is a tool that tells you how many months your company can keep operating before the cash in the bank runs out. You enter your current cash balance, your monthly operating expenses (the gross burn) and any recurring revenue, and the calculator returns your runway in months, your net burn, the date your cash reaches zero, and a month-by-month projection showing how the balance declines. If revenue is growing faster than expenses, the tool also shows the month you break even — the month when revenue equals expenses and your cash balance stops falling.

This startup runway calculator goes beyond a simple cash ÷ burn division. It projects the balance month by month with configurable revenue and expense growth rates, includes a scenario toggle for burn increases (a critical planning tool when you are considering hiring or a large purchase), and shows you the break-even month if one is achievable within the projection window. It also gives you the fundraising window — the date by which you should start raising your next round. Everything runs in your browser — no sign-up, no account, no upload, no tracking.

How to use this free runway calculator

1. Enter your cash on hand — the current balance in your operating account, plus any other cash you can spend on operations.
2. Enter your monthly expenses (gross burn) — payroll, rent, software, marketing, everything you spend in a typical month.
3. Enter your monthly revenue — the recurring revenue you actually collect in a typical month, not annualized contract value.
4. Optionally set revenue growth and expense growth per month. Use 0 if you want a flat projection.
5. Use the scenario dropdown to model a burn increase or decrease — a 20% or 50% jump simulates a hiring round or a large one-off spend.
6. Click Calculate runway. The tool shows your runway in months, your net burn, the zero-cash date, a month-by-month table, and a fundraising window.

The runway formula

The basic runway formula is simple:

Runway (months) = Cash on hand ÷ Net monthly burn

Where net monthly burn is:

Net burn = Gross burn − Monthly revenue

For example: $600,000 cash, $80,000 gross burn, $30,000 revenue. Net burn is $50,000, so runway is 12 months. A flat projection would show the cash balance reaching zero in month 12.

When revenue and expenses are both growing, the calculation becomes iterative. This tool projects the balance month by month rather than using the simple formula, which is important because a growing company's runway can be much longer than the flat formula suggests — or much shorter, if expenses grow faster than revenue.

Gross burn vs net burn

Gross burn is your total monthly operating expenses. Net burn is gross burn minus revenue. Net burn is the figure that matters for runway, but gross burn matters for a different reason: it tells you the size of the hole you need to fill with revenue or funding.

The distinction trips up founders who quote the wrong number. A company with $100k gross burn and $60k revenue has a net burn of $40k, not $100k. Runway is $cash ÷ $40k, not $cash ÷ $100k. When investors ask about burn, they usually mean net burn — the amount of cash you are actually consuming each month.

How much runway should a startup have?

Most investors and accelerators recommend at least 12 months of runway, and 18 to 24 months is preferable for a seed-stage company. The reasoning is straightforward:

The reason to start raising at 9–12 months is that fundraising takes time. The average seed round takes 4 to 6 months from first meeting to money in the bank. If you start with 6 months of runway, you may run out before the round closes. Starting with 12 months gives you a buffer if the round takes longer than expected — which it often does.

Why projecting month-by-month matters

The simple cash ÷ burn formula gives a single number. But real startups do not have flat revenue and flat expenses. Revenue grows — slowly at first, then faster. Expenses also grow — typically in steps as you hire, sign a new office lease or commit to a large annual contract. A month-by-month projection shows what the flat formula hides:

• Break-even month. If revenue grows fast enough, you may reach break-even before you run out of cash. The tool shows the month when revenue overtakes expenses and the balance stops falling.
• Cash trough. Even if you break even, you may dip close to zero before that happens. The month-by-month table shows the lowest point.
• Runway sensitivity to burn growth. If you plan to hire in Q3, you can model the increased burn and see how much runway it costs.

Scenario planning: why the burn toggle matters

The most common reason a startup runs out of cash is not that the plan was wrong, but that expenses grew faster than expected. The scenario toggle in this tool lets you model three important cases:

• Burn +20%. You hire two or three people or sign a larger office lease. What does that do to runway?
• Burn +50%. You make a serious bet — a large marketing commitment, an enterprise sales team, a new product line. What is the runway cost of that bet?
• Burn −20%. You trim costs in response to a slower-than-expected raise. How much runway does that buy you?

Founders who run these scenarios ahead of time make better decisions about when to hire, when to raise, and when to cut. Founders who do not run them tend to discover the answer when the bank balance is already low.

The fundraising window

The fundraising window is the date by which you should start raising your next round. The conventional rule is to start when you have 9 to 12 months of runway remaining, because the round itself will take 4 to 6 months to close. If you start at 12 months, you have a 6-month cushion. If you start at 6 months, you are raising from a position of weakness — investors can see your cash position (or at least your urgency), and the terms reflect it.

This tool calculates the fundraising window as the date 12 months before your zero-cash date. Treat it as the latest sensible date to start, not the earliest.

Common mistakes when calculating runway

• Using gross burn instead of net burn. If you have revenue, subtract it. Otherwise you overstate the runway and understate the urgency.
• Forgetting one-off costs. Annual insurance, bonuses, tax payments, legal fees and hardware refresh all hit the cash balance in specific months and often get missed in a flat projection.
• Assuming revenue will arrive when you expect. Enterprise deals slip. Collections take longer than invoices. Model a conservative version of revenue, not the optimistic plan.
• Ignoring cost growth. Payroll grows with hires and raises. Software subscriptions grow with users. Rent grows on renewal. A flat burn assumption usually understates future burn.
• Treating runway as a single number. Runway is a range, not a point. Run three scenarios — base, conservative and bad — and plan for the middle one.
• Waiting until runway is short to fundraise. By then you have lost leverage. Start at 9–12 months.

Frequently asked questions