How Many Months of Runway Do You Have? Three Numbers for Small Company Cash Flow

Why Cash Flow Matters More Than Profit

When I started my first AI writing tool company in 2020, I spent three months polishing the product. After launch, user growth was decent—monthly active users hit 10K, and I expanded the team to five. But by month six, I found my bank account had less than two months of payroll left. I panicked—not because the product was failing, but because I had burned too much too fast, and I had been staring at the vanity metric of "monthly revenue growth."

That experience taught me: the direct cause of death for a small company is always cash depletion, not negative profit. You can lose money for three years and survive, as long as cash keeps flowing. You can be profitable for a quarter and die suddenly because of unpaid invoices, a big purchase, or a one-time expense.

I later prioritized cash flow management above product planning. This article is a simple framework I've used for years: three core numbers plus a monthly decision checklist. It's not boring accounting theory—it's a tool to help you decide whether to cut a feature, hire, raise prices, or even dissolve the team.

Three Core Numbers: Breath, Pulse, Temperature

I ignore NPV or IRR. For a small team, three numbers are enough.

1. Cash Balance (Breath)

Cash you can access immediately—checking account, money market funds. Do not include credit lines, unpaid AR, or the founder's personal savings. These are external crutches, not the real blood flowing through your business.

2. Monthly Net Burn Rate (Pulse)

Net Burn = Total cash expenses (salaries, rent, servers, marketing, founder's meal reimbursement) — Total cash inflows (prepayments, collected customer payments, tax refunds).

If inflows exceed expenses, the burn rate is negative, meaning you're generating cash—best scenario. Most early-stage small teams have a positive burn rate ("burning money"). You don't need penny precision, but you must calculate it monthly, and be honest—include any money the founder personally advanced.

3. Remaining Runway (Temperature)

Runway (in months) = Cash Balance ÷ Monthly Net Burn Rate (when burn is positive). If burn is negative, runway is infinite—you can invest aggressively.

This number tells you how many months you have left to make mistakes. My personal rules:

• Runway < 3 months: Activate survival mode immediately. Stop all non-core expenses. Focus on activities that generate immediate cash (chase invoices, sell services, take on contract work). Only reduce headcount; no new hires. Pause all new product experiments.
• Runway 3–6 months: Cautious mode. Maintain the current team and product, but any commitment exceeding one month's burn must be personally approved by the founder. You can try small experiments, but set a stop-loss (e.g., spend $2K and kill if no results).
• Runway 6–12 months: Normal mode. Room for product iteration and growth experiments, but review cash flow monthly to ensure burn doesn't run away.
• Runway > 12 months: Expansion mode. You can hire and explore new directions, but still control burn—don't get drunk on cash.

Monthly Decision Checklist

On the first day (or first week) of every month, I spend 30 minutes on a "cash flow review." This is not a finance meeting—it's a decision meeting. Starting from those three numbers, I answer:

1. Did last month's net burn exceed my forecast?
   • If yes, identify the largest overshoot (server spike? new hire? more refunds?). Then decide whether to cut.
2. Does current cash balance cover the next two months of fixed expenses?
   • If not, trigger emergency: pause all non-essential outsourcing, require weekly budget reports from the team, personally follow up with large AR.
3. Is the remaining runway longer than 6 months?
   • If shorter, delay all "nice-to-have" features, cut unprofitable channels, even consider temporarily deferring salaries (but communicate honestly with the team—never silently delay).
4. Is any large expense coming soon?
   • E.g., annual cloud subscription renewal, trade show fees. Deduct that amount from cash balance two months ahead, then recalculate runway.
5. Is anyone on the team overworking to the point of decreasing efficiency?
   • Tight cash flow often leads to overworking the team for less reward. But long-term burnout triggers turnover, which increases hiring and training costs. Better to stretch the project timeline than to squeeze the team dry.

This list sounds basic, but each review has saved me from impulsive decisions. Once, chasing a trend, I added an AI feature that took two weeks to build but only brought a few hundred visitors, doubling the server cost. If I had checked the runway (only 5 months at that time), I would never have done it.

Cash Flow Management Is Not the Accountant's Job

I've seen too many small company founders dump cash flow issues on a part-time bookkeeper while they focus only on product. But an accountant records history—they don't make decisions. Monitoring and deciding on cash flow must be done by the CEO/founder, because only you know which expenses can be cut, which contracts can be delayed, which clients can be pushed to pay earlier.

My own practice: use a simple Google Sheet (or Feishu/Multidimensional Table) updated monthly with the three numbers and auto-calculated runway. Share it with key partners for visibility, but keep decision authority. If a partner disagrees on cutting a project, I show them the runway number—data reduces arguments.

One extra tip: maintain a good relationship with your bank. Most small company founders are afraid of dealing with banks, but banks' small business loans, account opening, and tax support are very useful. I have a partner bank—I talk to my relationship manager monthly about my company's status. That way, if I need temporary borrowing, I'm not a stranger.

Potential Failure Modes

This framework assumes you have clear records of income and expenses. In early-stage messy operations, it's common for founders to advance their own money, and small transactions get lost. My experience: at least start logging from month one, even if it's just 10 minutes per week recording all bank flows. A messy ledger will make you underestimate your burn rate and make optimistic but wrong decisions.

Another limitation: when the company grows rapidly (exponential revenue growth), net burn may turn negative and runway becomes infinite, which can make you complacent. But growth often brings operational complexity—AR increases, and expenses often rise ahead of revenue. So even if revenue is rising, do periodic cash flow forecasts based on future commitments, not just past numbers.

Wrapping Up

For a small company, cash flow is breathing. Without breath, the best product and strongest team can die in an instant. I'm no finance expert, and this isn't an advanced model—it's a survival checklist from someone who stepped in the mud. If you're running a small company, spend half an hour calculating your three numbers—then, based on your runway, adjust what you'll do tomorrow.

PaxLee