Startup Runway Calculator: Know Exactly When Your Cash Runs Out

Ask a founder how much cash is left in the bank, and most can answer instantly. Ask how many months that cash buys them, and the answers get vague fast. Runway is the single most important number in startup finance — it tells you how long you can keep building before you either raise more money, grow revenue, or shut down. If you do not know yours to within a month, you are flying blind.

The Startup Runway Calculator turns three numbers you already know — cash on hand, monthly burn rate, and monthly recurring revenue — into a precise runway figure expressed in months, weeks, and days, plus a projected out-of-cash date. It runs entirely in your browser, costs nothing, and requires no sign-up. No financial data ever leaves your device.

In this guide, we will walk through how the calculator works, the math behind runway and net burn, what the health thresholds actually mean, and how founders at every stage use runway planning to make better decisions.

Why Use the Startup Runway Calculator?

• See your out-of-cash date, not just a number. A raw "11 months" is abstract. A projected date — for example, early August next year — is something you can plan around, put on a calendar, and work backwards from.
• Accounts for revenue, not just spending. Naive runway math divides cash by total expenses. The calculator subtracts monthly recurring revenue from burn first, giving you the true net burn figure that investors and board members expect.
• Instant health assessment. The result is flagged as Critical (under 6 months), Caution (6–12 months), or Healthy (12+ months), so you immediately know whether you need to act now or can keep executing your plan.
• Detects profitability automatically. If your recurring revenue already covers your burn, the calculator tells you your runway is effectively unlimited — a genuinely useful milestone for bootstrapped businesses.
• Completely private. Every calculation runs client-side in your browser. Your cash position is sensitive; there is no reason to upload it to anyone's server, and here you never do.
• Zero friction. No account, no email, no paywall. Open the page, type three numbers, get your answer. Perfect for quick what-if checks during a board meeting or investor conversation.

Key Features

The conversion factors are precise rather than rough: one month is treated as 4.345 weeks and 30.4375 days, which matches the average Gregorian month. That matters when your runway is short — the difference between "9 weeks" and "10 weeks" can decide whether a hiring plan is viable.

The copy-summary feature is designed for the moment someone asks "where are we on cash?" in a meeting. You get a clean text block with every input and output, ready to paste into Slack, an email, or your board deck notes.

How to Use It

1. Open the Startup Runway Calculator.
2. Enter your cash on hand — the total spendable cash in your company bank accounts right now.
3. Enter your monthly burn rate — average total monthly expenses, including salaries, rent, software, contractors, and marketing.
4. Enter your monthly recurring revenue — predictable MRR. Leave it at zero if you have no revenue yet.
5. Click Calculate. You will see your net burn, runway in months, weeks, and days, the projected out-of-cash date, total expected revenue during the runway, and a health status badge.

Change any input and recalculate to run scenarios instantly: what if we cut burn by 15%? What if MRR grows to cover half the burn? The math is fast because it is simple — and simple is exactly what you want when stress-testing your company's survival.

Understanding Runway, Burn Rate, and Net Burn

Three terms come up constantly in startup finance, and mixing them up leads to bad decisions:

• Cash on hand — spendable money available right now: bank balances, not committed capital or unused credit.
• Gross burn rate — total monthly expenses. If you spend $95,000 a month, your gross burn is $95,000.
• Net burn — gross burn minus recurring revenue. This is the number that actually depletes your cash.

The core formula:

Runway (months) = Cash on hand ÷ (Monthly burn − Monthly revenue)

A worked example. Suppose your startup has $500,000 in the bank, spends $95,000 per month, and brings in $50,000 in MRR:

• Net burn = $95,000 − $50,000 = $45,000 per month
• Runway = $500,000 ÷ $45,000 ≈ 11.1 months
• In other units: roughly 48 weeks, or about 338 days
• If today is the start of September, your projected out-of-cash date lands in early August next year

Notice how different the picture looks from naive math. Dividing $500,000 by gross burn alone would give ~5.3 months — a Critical rating. Factoring in revenue more than doubles your runway and changes the entire strategic conversation. That is why investors always ask for net burn.

The health thresholds encode common founder and investor conventions:

• Under 6 months — Critical. You have two quarters or less of execution room. Fundraising typically takes 3–6 months, so you are already late if you need outside money. Cut costs now: pause hiring, renegotiate contracts, trim discretionary spend.
• 6–12 months — Caution. You have room to operate, but not to be passive. Start investor conversations, push revenue growth, and define milestones that justify the next round.
• 12+ months — Healthy. You can focus on product and growth with a real buffer. Keep monitoring monthly — runway shrinks faster than founders expect.
• Profitable — revenue covers burn. Your net burn is zero or negative. Cash accumulates instead of depleting. Runway is effectively unlimited; the constraint becomes opportunity, not survival.

One caution: the calculator assumes burn and revenue stay constant. Real startups are not constant. Revenue hopefully grows, burn often steps up after hiring, and one-off expenses (equipment, legal, taxes) create dips. Treat the output as a baseline scenario and recalculate monthly — or whenever a material number changes.

Practical Use Cases

The pre-seed founder

You left your job, saved $80,000, and are building nights and weekends with $3,500 in monthly personal-and-business costs and zero revenue. The calculator shows ~22.9 months of runway — Healthy territory. That number tells you how long you can iterate before needing income, and sets a hard deadline for finding product-market fit. Recalculate every month and watch the trend line, not just the value.

The funded startup planning the next raise

You raised a seed round 14 months ago. Cash is at $420,000, gross burn is $110,000, and MRR has climbed to $68,000. Net burn is $42,000, so runway is exactly 10 months — Caution. Series A timelines being what they are, you should be building your data room and scheduling first meetings now, not in month 8. The out-of-cash date gives your fundraise a non-negotiable deadline.

The bootstrapped business

No investors, no round, just customers. If your $31,000 MRR exceeds your $28,000 monthly costs, the calculator confirms you are profitable and your runway is unlimited. That single confirmation reframes every decision: you can take risks a runway-constrained competitor cannot, because time is on your side. If a big planned expense pushes burn above revenue temporarily, model it and see exactly how many months of buffer the dip consumes.

The agency or freelance team

Runway logic applies outside pure startups. An agency with $150,000 in cash, $60,000 monthly operating costs, and $52,000 in retainers has a net burn of $8,000 — about 18.75 months of cushion if retainers hold. That cushion determines whether you can hire ahead of demand, survive a lost client, or invest in a new service line. Update it whenever your client mix changes.

Best Practices

• Recalculate monthly, on a fixed date. Runway is a trend, not a snapshot. A runway that falls from 14 to 12 to 9 months over three months is a louder alarm than any single number.
• Always use net burn in investor conversations. Reporting gross burn when you have meaningful revenue understates your position and signals sloppy finance. Know both numbers cold.
• Be honest about burn. Include everything: salaries, contractor payments, software, cloud costs, taxes, and the irregular expenses you prefer to forget. Understating burn by 10% overstates runway by the same margin.
• Count only spendable cash. Committed-but-unclosed investment, unused venture debt, and personal guarantees are not runway. Model them as scenarios, not baseline.
• Plan against the out-of-cash date minus a buffer. If cash hits zero in August and fundraising takes four months, your real deadline to start is roughly February. Work backwards from the date, never forwards from today.
• Run downside scenarios. Model what happens if a major client churns, a hire accelerates burn, or revenue plateaus. The cheapest time to discover a problem is in a browser tab, not in your bank statement.

Start Planning Before the Alarm Sounds

Runway is the one metric that quietly governs every other decision a startup makes — hiring, pricing, product scope, and fundraising timing all hang off it. Calculating it takes under a minute with the Startup Runway Calculator: enter your cash, burn, and revenue, and see exactly how long you have and when the money runs out.

Do it today, write down the date, and check it monthly. Future-you, deciding whether to hire that engineer or sign that office lease, will be glad the answer was already on paper.

Related Tools You Might Like

• Net Worth Calculator — track total assets minus liabilities for the full personal or company financial picture
• Investment ROI Calculator — evaluate the return on any investment before you commit capital
• Profit Margin Calculator — check whether your pricing actually leaves money after costs

Happy calculating!