How to Build a 13-Week Cash Flow Forecast

Build a 13-week rolling cash flow forecast to track weekly inflows, outflows, and ending balances for operational planning.

1. Set up your weekly framework. Create a spreadsheet with 13 columns for each week and rows for cash inflows, cash outflows, and ending cash balance. Start with this week as Week 1. Include your current cash position as the starting balance.
2. Project weekly cash inflows. Map customer payments based on your receivables aging and collection patterns. If you collect 60% of invoices in 30 days and 30% in 60 days, schedule accordingly. Add other regular inflows like recurring revenue or seasonal patterns.
3. Schedule fixed weekly outflows. Enter payroll dates, rent, loan payments, and other fixed obligations on their exact due dates. Most businesses pay bi-weekly or semi-monthly payroll—mark those specific weeks. Include quarterly tax payments and annual insurance premiums.
4. Estimate variable weekly expenses. Project vendor payments based on your payment terms and purchase patterns. If you pay net-30 and spend $10,000 monthly on supplies, schedule $2,500 weekly starting 4 weeks out. Include utilities, fuel, and operational costs.
5. Calculate running cash balances. For each week, add inflows to the previous week's ending balance, then subtract outflows. This shows your projected cash position weekly. Flag any week where the balance drops below your minimum operating threshold.
6. Update weekly and roll forward. Every week, compare actual results to projections and adjust assumptions. Drop the completed week and add Week 14 to maintain a rolling 13-week view. Track your forecast accuracy to improve future projections.