Free business planning calculator
Cash Flow Forecast Calculator
Project monthly cash flow, ending balance, and business runway from revenue and expenses. Free small business cash flow forecasting tool — see if you run out of cash before it happens.
Enter the minimum numbers needed to get a result.
Updated live as you type.
Planning estimate only. It does not include taxes, overhead allocation, depreciation, discounts, or other business-specific adjustments.
A cash flow forecast projects future cash balances by comparing expected monthly revenue against expected monthly expenses. Unlike profit, it tracks actual money in and out — so a profitable business can still run out of cash if timing is off.
Formula and example
Net cash flow = Monthly revenue - Monthly expenses; Runway = Starting cash / |Net cash flow| (when negative)
With $15,000 starting cash, $12,000 revenue, and $9,500 expenses, net cash flow is +$2,500/month. After 12 months, ending cash is $45,000.
Methodology & assumptions
Last updated: 2026-06-11Calculation method
Projects a simple linear cash flow by subtracting average monthly expenses from average monthly revenue, then multiplying by the forecast period. Runway is calculated only when net cash flow is negative.
Data sources
Uses the numbers you enter and standard small-business finance formulas. Benchmark comparisons use HustleFin industry benchmark pages where available.
Limitations
Assumes flat revenue and expenses each month. Does not model seasonal variation, growth, one-time purchases, or tax payments. Best for ballpark planning.
Input definitions
- Starting cash balance: Cash on hand at the start of the period.
- Monthly revenue: Expected average monthly revenue.
- Monthly expenses: Expected average monthly expenses (all costs).
- Forecast months: Number of months to forecast.
Frequently asked questions
What is a cash flow forecast?+
A cash flow forecast projects your cash balance over time by estimating incoming revenue and outgoing expenses for each period. It answers: 'Will I run out of cash before my next revenue comes in?'
How is cash flow different from profit?+
Profit is revenue minus expenses on paper (accrual). Cash flow tracks actual money moving in and out. A profitable business can still run out of cash if customers pay late, expenses are front-loaded, or inventory builds up. Positive cash flow with low profit can also occur — e.g., when you collect fast but have lots of non-cash expenses like depreciation.
What is runway?+
Runway is the number of months until you run out of cash at your current burn rate. It only applies when you are spending more than you earn each month. Formula: Runway = Starting cash ÷ |Monthly net cash flow|. A business with $30,000 cash burning $5,000/month has 6 months of runway.
Should I include loan payments in expenses?+
Yes. Include all fixed cash outflows — loan payments, rent, payroll, and recurring subscriptions — in your monthly expenses figure. The cash flow forecast tracks actual money leaving your account, not just operating expenses.
How often should I update my cash flow forecast?+
Update monthly at minimum. Compare actuals to your forecast each month — if revenue or expenses deviate significantly, refresh the forecast forward. Fast-growing businesses or businesses with volatile revenue should review weekly.
What is a good cash flow for a small business?+
Positive cash flow means you generate more cash than you spend — essential for long-term survival. Most advisors recommend keeping 3-6 months of operating expenses as a cash reserve. Cash flow positivity is more important than profitability in the early stages of a business.
Can I have positive cash flow and still lose money?+
Yes. Cash flow and profit measure different things. You can have positive cash flow but a net loss if, for example, you collect customer deposits (cash in) before delivering the service (not yet revenue). Conversely, a profitable business can have negative cash flow if it extends long payment terms to customers.
What is a 13-week cash flow forecast?+
A 13-week (quarterly) cash flow forecast is a short-term weekly model used by CFOs and lenders to monitor near-term liquidity. It's more granular than a monthly model — tracking weekly inflows and outflows. This monthly calculator is best for annual planning; for a 13-week model, track by week.
Related guides
Go deeper with in-depth guides on the concepts behind this calculator.
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