Cash Flow Forecast Calculator

Why cash flow forecasting matters more than profit

A business can be profitable on paper and still run out of cash. This is because profit is an accounting concept that reflects revenue and expenses when they are accrued, not necessarily when cash actually moves. A profitable business can invoice clients, record revenue, and show a healthy margin while waiting 60 or 90 days to collect the cash. During that waiting period, it still needs to pay suppliers, employees, and landlords. If the cash is not there, the business cannot meet those obligations regardless of what the income statement says. Cash flow forecasting addresses this by projecting the actual timing of cash movements, not just the accounting outcome.

The cash flow forecast starts with the opening cash balance: the actual cash in the business at the start of the forecast period. Each month, cash inflows are added (actual receipts expected, not invoices raised) and cash outflows are subtracted (actual payments made, not expenses accrued). The result is the closing cash balance, which becomes the opening balance for the following month. Repeating this over the forecast period produces a month-by-month view of the cash position, including the months where the balance is lowest and the risk of running short is highest.

The most important output of a cash flow forecast is not the final balance but the lowest balance during the period. A business might have a healthy cash position at the end of the year but pass through a valley in month 4 where the balance drops to near zero. That valley is the risk point. Identifying it in advance gives the business time to act: draw on a line of credit, accelerate collections, delay non-critical payments, or adjust the timing of a large expenditure. A cash flow problem identified three months in advance is manageable. The same problem identified the week before payroll is a crisis.

Inflows vs revenue: the critical distinction

Cash inflows are not the same as revenue. Revenue is recorded when a sale is made; cash inflow occurs when the payment is received. If you have 45-day payment terms, the revenue from January sales arrives as cash in mid-March. For the cash flow forecast to be accurate, you need to model the timing of cash receipts based on your actual payment terms and collection experience. Businesses with long payment terms, high invoice volumes, or slow-paying clients face a structural gap between when revenue appears and when cash arrives. This gap is what cash flow forecasting is designed to quantify and manage.

Outflows and fixed vs variable timing

Cash outflows also have specific timing that may not match the period in which the expense is recognised. Quarterly insurance premiums, annual software licences, tax payments, and loan repayments create lumpy outflows that need to be placed in the correct month rather than averaged. In this simplified calculator, a constant monthly outflow is used for projection purposes. In a more detailed cash flow model, each significant payment would be placed in the specific month it is expected to occur, which produces a more accurate and useful forecast.

Using the forecast to plan borrowing

If the cash flow forecast projects a negative balance in a future month, the business needs to arrange financing before that month arrives. The required facility size is at least the depth of the negative balance plus a prudent buffer. A revolving line of credit is the most flexible instrument for managing short-term cash flow gaps, because it can be drawn when needed and repaid when cash improves. Arranging credit facilities when the business is in a strong position, rather than when it is already in a cash crisis, produces much better terms and greater lender confidence. The cash flow forecast is the document that makes this planning conversation with a banker or lender both specific and credible.