Startup Cash Runway Calculator — Calculate Burn Rate & Months of Runway
Free startup runway calculator calculates burn rate and cash runway. Determine exactly how many months your startup can survive with current cash and expenses. Essential for fundraising and financial planning.
Startup Cash Runway Calculator — Calculate Burn Rate & Months of Runway
Enter your cash balance, monthly expenses, and revenue to calculate your runway
Projected monthly increase in costs
Projected monthly revenue growth
How to Use Runway Calculator
Enter Current Cash Balance
Input your startup's total available cash, including bank balances and liquid reserves. This is your starting capital before monthly operations.
Input Monthly Expenses
Enter your total monthly cash outflows - salaries, rent, software, marketing, and all operational costs. This is your gross burn rate.
Add Monthly Revenue
Include all monthly revenue and cash inflows. The calculator will subtract this from expenses to determine your net burn rate.
Review Your Runway
See exactly how many months your startup can operate, when you'll run out of cash, and get actionable recommendations based on your runway length.
Key Features
Real-time runway calculations with live adjustments as you type
Gross and net burn rate analysis with automatic detection
Cash flow positive and break-even revenue target calculations
Visual runway timeline showing estimated cash depletion date
Color-coded risk assessment with actionable recommendations
Mobile-optimized interface for founders checking runway on-the-go
100% privacy-focused: all calculations happen in your browser
Comprehensive financial analysis including months and days of runway
What Is Cash Runway and Why It's the Lifeblood of Your Startup
Cash runway is the single most critical metric for any early-stage company. It represents the number of months your business can continue operating before running out of money, based on your current cash balance and monthly burn rate. Think of it as the fuel in your tank—it dictates how far you can go before you need to refuel (raise capital) or reach a destination (profitability).
In the volatile economic climate of 2025, investors are prioritizing sustainability over growth at all costs. A healthy runway gives you leverage in negotiations, the ability to weather market downturns, and the time to find true product-market fit. Conversely, running out of cash is the #1 reason startups fail, accounting for 38% of all post-mortems.
Critical Insight: Fundraising typically takes 6-9 months from first pitch to cash in the bank. If your runway drops below 9 months and you haven't started raising, you are effectively in the "danger zone" where desperation can force you into bad terms or bankruptcy.
How to Calculate Startup Runway: The Math Behind Survival
The formula for cash runway is simple, but the inputs require precision. It revolves around two core concepts: **Gross Burn** (total spending) and **Net Burn** (spending minus revenue).
Gross Burn Rate
Your total monthly operational expenses. Salaries, rent, server costs, marketing spend, and software subscriptions.
Net Burn Rate
Gross burn minus monthly revenue. This is the actual cash leaving your bank account each month.
If you have $300,000 in the bank and your net burn is $30,000/month, your runway is exactly 10 months ($300k / $30k). This means you have 10 months to either increase revenue, decrease expenses, or raise more money.
Real-World Example: The Pivot that Saved a Unicorn
Let's look at a hypothetical SaaS company, "CloudScale," to understand how runway dictates strategy.
The Situation (Jan 1st)
- Cash in Bank: $1,200,000
- Monthly Expenses: $150,000
- Monthly Revenue: $30,000
- Net Burn: $120,000
- Runway: 10 Months
The Strategic Decision
With only 10 months of runway, CloudScale realized they couldn't afford their aggressive hiring plan. They needed 18 months to hit the metrics required for Series A.
The Outcome (Feb 1st)
They froze hiring and cut non-essential software (saving $20k/mo) and focused entirely on sales (adding $10k/mo revenue). New net burn: $90k. New Runway: 13.3 Months. That extra quarter gave them enough time to land a major partnership.
Expert Tips for Extending Your Runway
The "Default Alive" Mindset: Ask yourself: "If we never raised another dollar, would we make it to profitability?" If the answer is no, you are "Default Dead." Prioritize getting to Default Alive before worrying about hyper-growth.
Negotiate Annual Upfronts: Offer customers a 15-20% discount if they pay annually instead of monthly. This brings cash in immediately, artificially boosting your bank balance and extending runway without raising equity.
Use Venture Debt Cautiously: Venture debt can extend runway by 3-6 months without dilution, but it adds a monthly interest payment that increases burn. Only use it if you have a clear path to the next equity round.
Cut Early, Cut Deep: If you need to reduce burn, do it once and do it deeper than you think necessary. "Death by a thousand cuts" (multiple small layoffs) destroys morale. One decisive restructure is better for culture and survival.
Common Runway Calculation Mistakes
Mistake 1: Confusing "Bookings" with Cash
Don't calculate runway based on signed contracts (bookings). Calculate it based on cash in the bank. A $100k contract that pays net-60 doesn't help you make payroll next week.
Mistake 2: Ignoring One-Off Expenses
Startups often forget "lumpy" expenses like annual server prepayments, insurance premiums, or legal fees for fundraising. Always add a 10-15% buffer to your burn rate.
Mistake 3: Assuming Linear Growth
It's dangerous to assume revenue will grow 10% MoM forever while expenses stay flat. Expenses usually grow in steps (hiring a new team), while revenue can be volatile.
Runway Benchmarks by Stage
| Stage | Target Runway | Primary Focus |
|---|---|---|
| Pre-Seed / Seed | 18-24 Months | Finding Product-Market Fit |
| Series A | 18-24 Months | Building a repeatable sales motion |
| Series B+ | 24+ Months | Scaling efficiently & unit economics |
When to Use This Calculator
Update your inputs every month after closing the books to keep a pulse on your survival date.
Model the impact of adding 3 engineers. Does it drop your runway below 12 months?
Calculate exactly how much you need to raise to reach your next major milestone with buffer.
Determine if you have enough time to build, launch, and sell a new product direction.
About the Author
Marko Hrvojević
Finance Expert, CPA with 12+ years in financial analysis and tax planning
Connect with MarkoFrequently Asked Questions
What is a healthy runway for a seed-stage startup?
For pre-seed and seed-stage startups, 18-24 months is the gold standard. This provides 12 months to find product-market fit and 6 months to raise the next round. Anything less than 12 months is considered high risk, as it leaves little margin for error or fundraising delays.
Should I calculate runway using gross burn or net burn?
Always use Net Burn Rate (Total Expenses - Revenue) to calculate your actual survival timeline. However, keep an eye on Gross Burn Rate as a measure of your spending efficiency. If your revenue suddenly drops to zero, your Gross Burn becomes your Net Burn, so it's your worst-case scenario baseline.
How do I calculate runway if my revenue is growing?
The basic formula (Cash / Current Net Burn) assumes flat growth, which is conservative and safe. To model growth, you need a dynamic forecast that accounts for increasing revenue and increasing expenses (hiring). Our calculator allows you to input growth rates for both revenue and expenses to see a more realistic projection.
Does credit card availability count as cash runway?
No. Never include credit lines or potential loans in your cash runway calculation. Runway is about *survival*, and relying on debt that you might not be able to service is a recipe for bankruptcy. Only count liquid cash in the bank that is yours to spend.
When should I start fundraising?
Start fundraising when you have 9-12 months of runway remaining. The average Series A process takes 6 months. starting at 12 months gives you leverage; starting at 3 months makes you desperate. If you have less than 6 months, consider extending runway by cutting costs before pitching.
What is the 'Default Alive' vs 'Default Dead' concept?
Coined by Paul Graham, 'Default Alive' means that based on your current growth rate and runway, you will reach profitability before running out of money. 'Default Dead' means you will run out of cash unless you raise more funds. Your primary goal should be to become Default Alive.
How often should I update my runway calculation?
Update your runway calculation monthly, immediately after closing your books. A single bad month of churn or an unexpected large expense can shift your zero-cash date by weeks or months. Constant vigilance prevents nasty surprises.
Can I extend runway without firing people?
Yes. Focus on non-labor costs first: cancel unused software, renegotiate server contracts (AWS/Google Cloud credits), move to a cheaper office or go remote, and reduce marketing spend to channels with proven ROI. On the revenue side, incentivize annual prepayments to bring cash in the door immediately.
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