Cash Flow Forecast Calculator

Cash flow measures the actual movement of money into and out of your business during a specific period. It is fundamentally different from profit: a business can be profitable on paper while running out of cash, and a cash-flow-positive business can be unprofitable. The difference comes from timing — revenue is recognized when earned (accrual accounting), but cash flow tracks when money actually arrives in your bank account. A company that invoices $100,000 in January but collects payment in April shows January profit but no January cash.

Free cash flow (FCF) is what remains after covering all operating expenses and capital expenditures: FCF = Operating Cash Flow - Capital Expenditures. This is the money available for debt repayment, dividends, reinvestment, or building reserves. Positive free cash flow is the clearest signal of a financially healthy business. Negative free cash flow can be acceptable during growth phases, but it must be funded by either reserves or external capital.

Working capital — the gap between current assets (cash, receivables, inventory) and current liabilities (payables, accrued expenses) — is the engine of cash flow. When customers pay slowly (high days sales outstanding), you need more working capital to cover operations while waiting. When you hold excess inventory, cash is trapped in unsold goods. When you pay suppliers faster than customers pay you, the gap widens. Managing these three levers — receivables, inventory, and payables — is how operationally excellent companies generate cash even in tight-margin industries.

Cash flow forecasting projects future inflows and outflows to predict when you will have surpluses or shortfalls. A 13-week rolling cash flow forecast is the standard for operational planning: short enough to be accurate, long enough to act on. The forecast should include every known cash event — payroll dates, rent, loan payments, tax deadlines, expected customer payments — and model uncertainty around variable items like new sales and collection timing.

Start by calculating your cash conversion cycle: Days Sales Outstanding (DSO) + Days Inventory Outstanding (DIO) - Days Payable Outstanding (DPO). This tells you how many days of working capital your business model requires. If your CCC is 60 days and your monthly expenses are $100,000, you need approximately $200,000 in working capital at all times. Reducing your CCC by even 10 days frees up significant cash.

Attack receivables first — it is usually the fastest lever. Invoice immediately upon delivery, not at month-end. Require deposits or milestone payments for large projects. Offer early payment discounts for customers who consistently pay late. For chronically slow payers, switch to prepayment or credit card terms. Every day you shorten DSO directly reduces your working capital requirement.

Build a 13-week rolling cash flow forecast and update it weekly. Include all known inflows (confirmed orders, expected collections, scheduled payments) and outflows (payroll, rent, suppliers, tax payments, loan service). Flag any week where projected cash drops below your minimum threshold and take action before it happens — whether that means accelerating collections, delaying discretionary purchases, or drawing on a credit line. The companies that manage cash best are the ones that see problems 6-8 weeks before they hit.