Startup Runway Calculator — How Long Until Your Money Runs Out
Calculate how many months your startup can survive before funding runs out. Know your runway before your bank balance forces the conversation.
Every founder has had that moment — staring at the bank balance at 2am, trying to figure out how many months of oxygen are left. Runway is the single most important number for any early-stage startup, and it's surprisingly easy to miscalculate. The CalcHub Startup Runway Calculator gives you a clear-eyed answer in seconds.
What Is Runway, Exactly?
Runway is how many months your startup can operate before it runs out of cash, assuming current spending and revenue stay the same. It's a ceiling, not a forecast — it tells you when you must either reach profitability or close a new funding round.
Runway (months) = Cash on Hand / Net Burn RateNet burn rate = total monthly expenses minus monthly revenue. If you're spending ₹15 lakhs a month and bringing in ₹3 lakhs, your net burn is ₹12 lakhs.
How to Use the Calculator
- Cash balance — total money in the bank right now, including any invested capital not yet deployed
- Monthly expenses — all costs: salaries, SaaS tools, office, cloud infra, contractor fees
- Monthly revenue — actual collected revenue, not ARR or bookings
- Calculate — get runway in months plus your projected "zero day"
Scenario Planning Table
| Cash Balance | Monthly Expenses | Monthly Revenue | Net Burn | Runway |
|---|---|---|---|---|
| ₹60L | ₹15L | ₹0 | ₹15L | 4 months |
| ₹60L | ₹15L | ₹5L | ₹10L | 6 months |
| ₹1Cr | ₹20L | ₹8L | ₹12L | 8.3 months |
| ₹2Cr | ₹25L | ₹10L | ₹15L | 13.3 months |
What Counts as "Expenses"?
People routinely undercount burn. A realistic monthly burn includes:
- Salaries + PF/ESI/gratuity (full loaded cost, not just CTC)
- Contractor and freelancer payments
- AWS/GCP/Azure bills — these scale faster than you expect
- SaaS subscriptions (Slack, Notion, HubSpot, etc.)
- Rent and utilities
- Legal and compliance (monthly retainers)
- Founder salaries — yes, even if below market
The 18-Month Rule
Most experienced investors suggest maintaining at least 18 months of runway at all times. Why 18? It gives you 12 months to execute your current plan plus 6 months to fundraise without desperation showing in the room.
Desperation is expensive. Founders raising with 2 months of runway take worse terms, give up more equity, and often accept the first offer instead of the best one.
Extending Runway Without a New Round
- Cut monthly software costs — do an audit; most startups overpay for tools they use 20% of
- Defer non-critical hires — a hire you make at month 2 costs more total than one you make at month 6
- Negotiate payment terms — ask vendors for net-60 instead of net-30
- Revenue-based financing — if you have MRR, platforms like Velocity or Recur Club can front capital without dilution
How is runway different from burn rate?
Burn rate is how fast you're spending money each month. Runway is how long that spending can continue before cash hits zero. Burn rate is the input; runway is the output.
Should I use gross burn or net burn for runway?
Net burn (expenses minus revenue) gives the most accurate runway figure. Gross burn (just expenses) is useful for stress-testing: if revenue suddenly disappears, how long do you last? Most investors ask for both.
What's a safe runway to have before starting to fundraise?
Start fundraising when you have at least 9–12 months left. That gives you time to run a real process, get competing term sheets, and not look panicked. Less than 6 months and you're negotiating from weakness.