A quick note before you read: This guide is general education only—not financial, tax, or legal advice. Every business is different, and the right decisions for yours depend on your specific situation. Treat these as starting-point guidelines, and consult a qualified accountant or financial professional before acting on anything here.
More businesses die from running out of cash than from a lack of profit. A company can be "profitable" on paper and still go under because the money it’s owed hasn’t arrived yet while the bills are due now. That gap—timing—is what cash flow management is about. Here’s how to stay ahead of it.
Cash flow vs. profit (they’re not the same)
This trips up a lot of founders, so it’s worth being clear:
- Revenue is what you earn.
- Profit is what’s left after expenses.
- Cash flow is timing—when money actually moves in and out of your bank account.
You can be profitable and still cash-poor if customers pay you slowly while your own costs are due quickly. Watching profit alone can hide a cash problem until it’s an emergency. Watch the cash.
Know your burn rate
Your burn rate is simply how much cash your business spends in a month, net of what comes in. Add up your monthly outflows—rent, software, contractors, your own pay, everything—and subtract your reliable monthly inflows. The result is what you’re "burning" each month.
If you’re spending more than you bring in, that number tells you how fast your cushion is shrinking. If you’re bringing in more than you spend, congratulations—you’re building runway instead of using it.
Calculate your runway
Runway is how many months you can keep operating before you run out of cash, assuming things stay roughly the same. The math is simple:
Runway (months) = Cash in the bank ÷ Monthly burn rate
Knowing this number changes how you make decisions. Three months of runway and twelve months of runway are completely different situations—one calls for urgency, the other for patience. Many founders avoid calculating it because they’re afraid of the answer. Knowing is always better than not knowing.
Forecast the next 13 weeks
Monthly thinking is too coarse for cash, because a single big bill or a late payment can sink you mid-month. A 13-week cash forecast (one business quarter, week by week) is the small-business standard for good reason. For each of the next 13 weeks, estimate:
- Cash coming in (expected customer payments).
- Cash going out (bills, payroll, recurring costs, one-off expenses).
- Your running balance at the end of each week.
This surfaces the tight weeks before they arrive, so you can chase a receivable, delay a purchase, or arrange a buffer in advance instead of scrambling. The free Milk Spider finance toolkit includes a ready-made 13-week forecast you can fill in.
Free download: Milk Spider Finance Toolkit (Excel) — a 13-week cash-flow forecast and a break-even calculator you can fill in.
Set a minimum cash buffer
Decide on a floor—a cash balance you won’t let yourself drop below without taking action. When your forecast shows you approaching that floor, that’s the trigger to act: collect faster, cut a cost, or raise capital. Having the line drawn in advance keeps a tight month from becoming a panicked one.
Speed up the cash cycle
The faster money comes in and the slower it sensibly goes out, the healthier your cash position. A few practical levers:
- Invoice promptly and make it easy to pay.
- Shorten payment terms where you can, or take deposits up front.
- Follow up on late payments quickly and consistently—politely, but without delay.
- Time large outflows so they don’t all land in the same week.
Small improvements in timing add up to a much more stable business.
A simple weekly habit
You don’t need to become an accountant. A 15-minute weekly check-in—review your balance, upcoming bills, and what you’re owed, then update your forecast—keeps you in control. The founders who never get blindsided by cash aren’t the ones with the most money; they’re the ones who look at it regularly.
FAQ
What’s a healthy amount of runway?
It depends on your business and how predictable your revenue is, but more is generally safer. Many founders aim to keep a comfortable cushion and act well before it runs thin. Talk to a financial professional about what’s right for your situation.
How is burn rate different from expenses?
Expenses are what you spend; burn rate is what you spend net of income—the actual rate your cash cushion is depleting (or growing). It’s the number that determines your runway.
Why forecast 13 weeks specifically?
It’s one business quarter—long enough to see trouble coming, short enough to estimate with reasonable accuracy. Weekly granularity catches mid-month crunches that monthly numbers hide.
Do I need special software for this?
No. A simple spreadsheet works to start. The discipline of updating it weekly matters far more than the tool.