How to Build a 13-Week Cash Flow Forecast
A 13-week cash flow forecast lists the money you expect to come in and go out each week for the next quarter, so a shortfall shows up weeks before it reaches the bank. This page explains the method, works one through for a fictional landscaping company, and offers the result as a sample file.
By Matthew Dettman, ChFC, CLU, founder of Second Difference Solutions. Updated .
What is a 13-week cash flow forecast?
It is a short, practical plan for cash, kept by the week. You start from the money in the bank today, list what you expect to receive and what you expect to pay in each of the next 13 weeks, and carry the balance forward one week at a time. The result shows the week cash is lowest and how far ahead of it you are.
It answers a different question from the profit and loss. Profit counts revenue when it is earned and expenses when they are incurred; the forecast counts money when it moves. The cash flow statement guide explains why the two drift apart, and why profitable businesses run out of cash names the 13-week forecast as the most actionable step in watching both.
How do you build a 13-week cash forecast?
- Start from the bank. Use the balance in your business bank account on the day you build the sheet.
- List receipts by week. Put each customer payment you expect in the week you expect the money: invoices coming due, deposits, regular sales. Where you have no detail yet, last year's figure for the same month spread across its weeks is a reasonable placeholder.
- List payments by week. Payroll dates, rent, loan payments and tax deadlines each go in the week they are due.
- Roll the balance forward. Ending cash equals starting cash plus receipts minus payments, and each week starts where the last one ended.
- Find the low point. The lowest ending balance in the 13 weeks is the number to watch, and the week it falls in is your deadline.
- Update it every week. Replace the finished week with what actually happened and add a new week at the end.
Worked example: a fictional landscaping company
This example uses the books of a fictional landscaping company, the same fictional sample company as the landscaping case study, so the figures match that page. The forecast is built as of December 31, 2025, for the 13 weeks that start January 1, 2026, using only what the company's 2025 reports show. The example uses last year's income for each month as a stand-in for what customers will pay that month, and last year's costs as a stand-in for what the business will pay out. Income is not the same as cash collected: an invoice still unpaid at month end is income but not yet cash, so a real forecast uses the dates customers actually pay.
The inputs
- Starting cash: the checking account held $213,787.45 on December 31, 2025. The example follows that one account.
- Receipts: each week takes the 2025 income of the month it starts in, split evenly across that month's weeks. Jan 2025 income of $11,375.00 over 5 weeks is $2,275.00 a week; Feb 2025 income of $12,187.52 over 4 weeks is $3,046.88 a week; Mar 2025 income of $15,437.52 over 4 weeks is $3,859.38 a week.
- Payments: 2025 revenue of $221,242.64 minus operating income of $101,739.28 leaves $119,503.36 of cost of goods sold and operating expenses. Divided by 52 weeks, that is $2,298.14 a week.
The arithmetic, week by week
Week 1 starts with $213,787.45, adds $2,275.00 of receipts and subtracts $2,298.14 of payments, ending at $213,764.31. Week 2 starts from that figure, and so on to week 13. Amounts are in dollars and cents so every line can be checked by hand.
13-week cash forecast for a fictional landscaping company, weeks starting January 1, 2026
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| Week | Starts | Starting cash | Receipts | Payments | Net change | Ending cash |
|---|---|---|---|---|---|---|
| 1 | Jan 1 | $213,787.45 | $2,275.00 | $2,298.14 | -$23.14 | $213,764.31 |
| 2 | Jan 8 | $213,764.31 | $2,275.00 | $2,298.14 | -$23.14 | $213,741.17 |
| 3 | Jan 15 | $213,741.17 | $2,275.00 | $2,298.14 | -$23.14 | $213,718.03 |
| 4 | Jan 22 | $213,718.03 | $2,275.00 | $2,298.14 | -$23.14 | $213,694.89 |
| 5 | Jan 29 | $213,694.89 | $2,275.00 | $2,298.14 | -$23.14 | $213,671.75 |
| 6 | Feb 5 | $213,671.75 | $3,046.88 | $2,298.14 | $748.74 | $214,420.49 |
| 7 | Feb 12 | $214,420.49 | $3,046.88 | $2,298.14 | $748.74 | $215,169.23 |
| 8 | Feb 19 | $215,169.23 | $3,046.88 | $2,298.14 | $748.74 | $215,917.97 |
| 9 | Feb 26 | $215,917.97 | $3,046.88 | $2,298.14 | $748.74 | $216,666.71 |
| 10 | Mar 5 | $216,666.71 | $3,859.38 | $2,298.14 | $1,561.24 | $218,227.95 |
| 11 | Mar 12 | $218,227.95 | $3,859.38 | $2,298.14 | $1,561.24 | $219,789.19 |
| 12 | Mar 19 | $219,789.19 | $3,859.38 | $2,298.14 | $1,561.24 | $221,350.43 |
| 13 | Mar 26 | $221,350.43 | $3,859.38 | $2,298.14 | $1,561.24 | $222,911.67 |
| Total | $213,787.45 | $39,000.04 | $29,875.82 | $9,124.22 | $222,911.67 |
Fictional sample data for a fictional landscaping company; not real business figures.
Reading the result
In the 5 weeks that take January's receipts, each week brings in $2,275.00 and pays out $2,298.14, a net change of -$23.14. Cash is lowest at the end of week 5 (February 4, 2026), at $213,671.75. From February the weekly receipts exceed the weekly payments, and week 13 ends at $222,911.67. To check the whole sheet: $213,787.45 of starting cash plus $39,000.04 of receipts minus $29,875.82 of payments equals $222,911.67, a rise of $9,124.22 over the 13 weeks.
For this company the sheet shows no squeeze: January runs slightly behind, and February and March make it up. Part of the January dip comes from the method itself, which spreads costs evenly across the year while receipts follow the season. The value of the exercise is knowing that before the quarter starts, and seeing at once what would change it.
What the example leaves out
- One-off payments. The example uses only the profit and loss, so loan principal, owner draws, equipment purchases and tax deposits are not in it. A real forecast adds each one in the week it is due, and any of these can create the low point.
- Items below operating income. Interest and other items listed after operating income on the profit and loss are left out of the payments.
- Seasonal costs. Payments here are a flat weekly average. If your costs rise and fall with the season, use last year's monthly costs the same way the receipts use last year's monthly income.
- This year's pace. Receipts follow last year's months. A business that is growing or shrinking should replace them with the invoices and bookings it actually has, which is why the sheet is updated weekly.
The case study reads six years of the same fictional company's books, and the landscaping industry page covers landscaping businesses more broadly. This example is analysis of fictional figures, not advice for your business.
How does this compare with the 2diff Business forecast?
2diff Business Silver by 2diff.io reads your QuickBooks® Online reports and projects the profit and loss, balance sheet and cash flow by year, quarter or month. Under its Drivers method you set a minimum cash balance, and the forecast shows any Needed Financing when cash would fall below it. That is a longer view built from your statements; the 13-week sheet is the short weekly view you keep alongside it. See the 2diff Business guide for the forecast settings.
2diff Business by 2diff.io builds statements, ratios and a forecast from a few annual figures you type in, with no accounting software required. See 2diff Business from your own figures.
Cash Forecast Questions
What is a 13-week cash flow forecast?
A week-by-week list of the cash a business expects to receive and pay over the next 13 weeks, starting from today's bank balance. Each week's ending cash is its starting cash plus receipts minus payments, and it becomes the next week's starting cash. Thirteen weeks is 91 days, about one quarter, which gives lead time to act if a shortfall is approaching.
What is the difference between profit and cash flow?
Profit is revenue minus expenses for a period, counted when earned or incurred. Cash flow is the money that actually entered and left the bank, so unpaid invoices or inventory purchases can leave a profitable business short of cash.
How often should I update a 13-week cash forecast?
Weekly. Replace the week that just ended with what actually came in and went out, add a new week at the end so the sheet still looks 13 weeks ahead, and move any receipt or payment whose date has changed.
Does 2diff Business build a 13-week cash forecast?
Not a weekly one. 2diff Business's forecast projects your statements by year, quarter or month, and its Drivers method includes a projected cash flow. The 13-week sheet on this page is a separate weekly plan you keep yourself; the sample file gives you a starting layout.
Related
- Why a Trend Line Is Not a Cash Flow ForecastForecast with drivers, read a 12-month forecast, and act when it turns negative.
- Financial Ratios ExplainedWhat each ratio measures, which statement it reads, and a worked example.
- Financial Metrics for a Landscaping BusinessWhich metrics matter for the trade, and how to read seasonality in monthly revenue.