A 13-week cash flow forecast lists, week by week, the cash you expect to come in and go out, and the balance left at the end of each week. In our example, a business that ends the quarter $2,200 ahead still drops to $300 in week 10, and moving one supplier order removes the risk.
Why 13 weeks?
It’s one quarter: short enough to estimate with confidence, long enough to see problems coming. Profit tells you whether the business makes money over time; cash flow tells you whether you can pay the bills this week.
How to build one
- Starting cash: your bank balance today.
- Cash in, by week: expected customer payments, based on when they actually pay, not when you invoice.
- Cash out, by week: payroll, rent, suppliers, loan payments, subscriptions and other bills on their due dates.
- Ending balance = starting balance + cash in − cash out. It becomes next week’s starting balance.
- Update it every week with real numbers and roll it forward one week.
A worked example
Starting with $8,000. Payroll of $2,800 every two weeks, rent of $2,000 every four weeks, $600 a week of other costs and two $4,000 inventory orders:
| Week | Cash in | Cash out | Ending balance |
|---|---|---|---|
| 1 | $3,000 | $2,600 | $8,400 |
| 2 | $2,500 | $3,400 | $7,500 |
| 3 | $3,200 | $4,600 | $6,100 |
| 4 | $1,800 | $3,400 | $4,500 |
| 5 | $3,000 | $2,600 | $4,900 |
| 6 | $2,600 | $3,400 | $4,100 |
| 7 | $2,900 | $600 | $6,400 |
| 8 | $1,500 | $7,400 | $500 |
| 9 | $3,100 | $2,600 | $1,000 |
| 10 | $2,700 | $3,400 | $300 |
| 11 | $3,000 | $600 | $2,700 |
| 12 | $2,200 | $3,400 | $1,500 |
| 13 | $3,300 | $2,600 | $2,200 |
The second inventory order lands in week 8, a slow sales week, and the balance falls to $500, then $300 in week 10. One late customer payment would mean a missed payroll. Moving that order to week 11 keeps the lowest balance at $1,500, with the same $2,200 at the end.
What to do when you spot a low week
- Move or split large purchases, like the inventory order above.
- Ask customers to pay sooner, for example with deposits or shorter payment terms.
- Ask suppliers for longer terms on a specific bill.
- Keep a cash buffer of a few weeks of fixed costs once you can.
- Arrange a credit line early, before you need it, if a shortfall still looks likely.
More questions
What is a cash flow forecast?
An estimate of the cash coming in and going out over a period, usually by week or month, showing the expected balance at each step.
How do I make a cash flow forecast in Excel or Google Sheets?
Put weeks across the columns and cash in and cash out items down the rows. Add a row for the ending balance that equals the previous balance plus cash in minus cash out.
What’s the difference between a cash flow forecast and a budget?
A budget plans income and costs for the period; a cash flow forecast focuses on the timing of actual payments, so it shows when you might run short.
How often should I update my cash flow forecast?
Weekly for a 13-week forecast: replace estimates with real numbers and add a new week at the end.
The bottom line
A business can be profitable and still run out of cash in a bad week. A 13-week forecast, updated every week, shows those weeks in advance so you can move a payment, collect sooner or line up help in time.
Sources
This article is for educational purposes only and is not business or financial advice. The example business and figures are illustrative.