A 13-week cash flow forecast is the single most important financial tool for any company between $5M and $50M. It answers the only question that actually kills companies: will we run out of cash?
Why 13 Weeks?
Thirteen weeks is one quarter. It’s long enough to see trends and short enough to be accurate. Weekly granularity catches timing issues that monthly forecasts miss — like the week when payroll, rent, and a vendor payment all hit simultaneously.
Building the Forecast
Step 1: Start with your bank balance
Today’s actual cash balance. Not projected, not adjusted — the real number.
Step 2: Map your cash inflows by week
Expected customer payments (use your AR aging), any committed new deals, recurring revenue collections, and other income. Be conservative — use historical collection patterns, not invoice dates.
Step 3: Map your cash outflows by week
Payroll (including taxes), rent, vendor payments (use your AP aging), loan payments, and any committed capital expenditures. Don’t forget quarterly payments like insurance, taxes, and annual subscriptions.
Step 4: Calculate weekly ending balance
Starting cash + inflows – outflows = ending cash. Each week’s ending balance becomes the next week’s starting balance.
Step 5: Set your floor
Define the minimum cash balance you’re comfortable with. Two months of operating expenses is a reasonable floor. If the forecast shows you dropping below this level, you have lead time to act — cut costs, accelerate collections, or arrange financing.
The Monday Morning Ritual
Every Monday: update actual results for last week, roll the forecast forward one week, and review the next 4 weeks for any concerns. This takes 15-20 minutes once the model is built. It’s the highest-ROI 20 minutes of your week.
Do This Monday
- Open a spreadsheet. 15 columns: labels + 13 weeks. Rows: starting cash, each inflow source, each outflow category, ending cash.
- Fill in everything you know with certainty: payroll dates, rent, committed payments. Then layer in expected collections from your AR aging.
- Set a recurring Monday morning calendar block: ‘Cash Flow Forecast Update.’ 20 minutes. Non-negotiable.
For ongoing cash management beyond the forecast, see our Cash Flow Management services — we build and maintain these systems for growing companies every day.
If you want help building a cash flow forecasting system, book a free consultation →