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13-Week Cash Flow Builder: Forecast Weekly Cash and Spot Shortfalls
A 13-week cash flow shows what your bank balance will do each week for the next quarter. It works because it is built from actual expected receipts and payments, not from the P&L, so it catches timing problems that profit hides.
Enter opening cash and a minimum liquidity floor, then edit the receipt and disbursement lines. Each line repeats on the schedule you set. You get the 13-week table, ending cash by week, the lowest-cash week and a shortfall flag, plus a CSV export. The example lines are illustrative; replace them with yours.
Starting point
Cash receipts
Cash disbursements
Each line repeats every N weeks starting in the week shown. Enter 0 for a one-time item. Amounts are positive; disbursements are subtracted.
Your results
Lowest ending cash
$235,000
In week 1.
Ending cash, week 13
$1,555,000
Ending cash by week
Free template · Excel workbook
13-Week Cash Flow Forecast Workbook
A direct-method 13-week cash forecast with receipts and disbursement lines, minimum liquidity, and weekly variance tracking.
Illustrative example values are prefilled; replace them with your own. Everything is calculated in your browser, and Performis does not store what you enter. Our analytics record which calculator was used and a few summary figures, such as a rounded result.
| Week | Opening | Receipts | Disbursements | Net | Ending |
|---|---|---|---|---|---|
| 1 | $250,000 | $380,000 | $395,000 | -$15,000 | $235,000 |
| 2 | $235,000 | $380,000 | $140,000 | $240,000 | $475,000 |
| 3 | $475,000 | $395,000 | $410,000 | -$15,000 | $460,000 |
| 4 | $460,000 | $380,000 | $140,000 | $240,000 | $700,000 |
| 5 | $700,000 | $380,000 | $395,000 | -$15,000 | $685,000 |
| 6 | $685,000 | $380,000 | $170,000 | $210,000 | $895,000 |
| 7 | $895,000 | $395,000 | $410,000 | -$15,000 | $880,000 |
| 8 | $880,000 | $380,000 | $140,000 | $240,000 | $1,120,000 |
| 9 | $1,120,000 | $380,000 | $395,000 | -$15,000 | $1,105,000 |
| 10 | $1,105,000 | $380,000 | $140,000 | $240,000 | $1,345,000 |
| 11 | $1,345,000 | $395,000 | $410,000 | -$15,000 | $1,330,000 |
| 12 | $1,330,000 | $380,000 | $140,000 | $240,000 | $1,570,000 |
| 13 | $1,570,000 | $380,000 | $395,000 | -$15,000 | $1,555,000 |
Shaded rows are below your minimum liquidity.
The formulas
- Net cash flow (week)
- Total receipts − total disbursements
- Ending cash (week)
- Opening cash + receipts − disbursements
- Opening cash (next week)
- Equals the prior week’s ending cash
- Line amount in a week
- Amount if week ≥ first week and (week − first week) is a multiple of the repeat interval; once only if interval is 0
- Shortfall
- Minimum liquidity − lowest ending cash, if positive
How to interpret your result
Find the low point first
The lowest-cash week and its size set how much cushion or funding you need and when you must arrange it. The date matters as much as the amount.
Treat a flag as an early warning, not a verdict
A shortfall in week 8 leaves weeks to move collections, stretch a payment or draw a facility. The same shortfall in week 2 is a different conversation.
Test your receipts, not your costs
Collections timing is usually the largest uncertainty. Delay the receipts lines by a week or two and see what happens to the low point.
Update it every week
The forecast earns its value when you replace week one with actuals and roll the horizon forward. A stale forecast gives false comfort.
Simplified lines are a starting point
Real forecasts break collections into customers and invoices and payables into vendors and runs. Use this to size the problem, then build the detail.
Frequently asked questions
What is a 13-week cash flow forecast?
A direct-method forecast of cash receipts and disbursements for the next 13 weeks, week by week. It starts with opening cash and ends with a projected balance each week, so you can see when cash is tight before it happens.
How do I build a 13-week cash flow?
List the cash you expect to receive (collections, other receipts) and the cash you expect to pay (payroll, suppliers, rent, debt service, taxes). Give each line an amount, how often it recurs and its first week. The builder adds them up by week from your opening cash.
How are repeating lines handled?
Each line has an amount, a repeat interval in weeks and a first week. Every 1 is weekly, 2 is biweekly, 4 is about monthly. Enter 0 for a one-time item in the first week shown.
What does the minimum liquidity setting do?
It is the cash floor you want to stay above, such as a covenant minimum or a payroll buffer. Any week that ends below it is flagged, and the tool reports the first breach week and the deepest gap.
Can I export the table?
Yes. Download the week-by-week table as a CSV file. The file is created in your browser and nothing is uploaded.
Is my data stored or sent anywhere?
No. All calculations run in your browser and nothing you enter is collected or saved.
Take it further with a template
Free template · Excel workbook
13-Week Cash Flow Forecast Workbook
A direct-method 13-week cash forecast with receipts and disbursement lines, minimum liquidity, and weekly variance tracking.
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