Cash Flow Calculation: Methods Every Small Business Needs

You can be profitable on paper and still run out of cash. Cash flow is the actual movement of money in and out of your business — and understanding it is the difference between surviving a slow month and going under. Here are the three methods for calculating it.

Method 1: Direct Cash Flow

The direct method tracks every cash receipt and cash payment directly. It's the most accurate picture of what's actually in your account.

• Add up all cash received from customers
• Add any other cash inflows (grants, loan proceeds, asset sales)
• Subtract cash paid to suppliers
• Subtract wages, rent, utilities, and operating costs
• Subtract tax payments
• Result = Net Operating Cash Flow

Method 2: Indirect Cash Flow

The indirect method starts with net profit and adjusts for non-cash items. This is what most accountants use and what appears on formal cash flow statements.

• Start with net profit
• Add back depreciation and amortisation (non-cash expenses)
• Adjust for changes in accounts receivable (up = cash out, down = cash in)
• Adjust for changes in accounts payable (up = cash in, down = cash out)
• Adjust for inventory changes
• Result = Net Operating Cash Flow

Method 3: 13-Week Cash Flow Forecast

This is a rolling forecast that projects your cash position week by week for the next quarter. It's not about accuracy — it's about visibility. If week 8 shows your balance going negative, you have 8 weeks to do something about it.

Warning Signs to Watch For

• Outstanding receivables growing faster than revenue
• Profit up but cash balance down (classic accrual trap)
• Relying on the overdraft at the same time each month
• Paying suppliers late to cover payroll
• Revenue is seasonal but costs are fixed

How Faster Invoicing Improves Cash Flow

Every day between completing work and sending an invoice is a day of free credit to your client. If you invoice immediately on completion and use Net 14 terms, you'll typically be paid 2–3 weeks faster than if you batch invoices monthly. For a business turning over $500k/year, that's $20–30k less you need in working capital.