What it means
A 13-week cash flow forecast lists, week by week, the cash you expect to come in and go out over the next quarter. It's built from real dates: when payroll runs, when bills are due, when each customer is likely to pay. The result is a projected bank balance at the end of each week.
Runway tells you roughly how many months you have. This tells you which Friday is tight.
Start from today's bank balance. Add expected receipts in the week they'll land, based on how customers actually pay rather than their terms. Subtract payments in the week they'll go out.
Each week, replace the week that just ended with actuals, compare them to what you forecast, and add a new week at the end so the view always reaches 13 weeks ahead. It comes from the bank, the bill-pay queue and the payroll calendar, not from the P&L.
Acme has $300,000 in the bank. Payroll of $120,000 runs in weeks 2 and 4. A $150,000 customer invoice is due in week 3, but that customer usually pays two weeks late. On a monthly view, March looks fine. Leaving other costs aside, the weekly view shows $180,000 after the first payroll and $60,000 after the second, with the payment not arriving until week 5. That's a month's warning, enough time to chase the customer or move a bill.
Lenders and boards ask for one when cash is tight, and it's useful whenever payroll dates and customer receipts don't line up.
Why it matters. Monthly runway hides the week payroll lands before a big customer pays. When cash is tight, this is the forecast lenders and boards ask for.
Try it with your numbers
Change any number. The working below updates as you type.
Closing cash = Opening cash + Receipts − Payments, rolled forward 13 weeksWhen customers actually pay, not when you invoice.
Payroll, rent and vendors, spread by week.
An annual prepayment, a tax bill, a bonus run.
Lowest cash, week 4
$10,000
How it’s worked out
- 1Each ordinary week$60,000 − $50,000$10,000
- 2Week 4, with the one-off$180,000 + $60,000 − $230,000$10,000
- 3Lowest point, week 4$180,000 + $60,000 − $230,000$10,000
- 4Cash after 13 weeks$150,000 + $780,000 − $830,000$100,000
| Week | Opening | Receipts | Payments | Closing |
|---|---|---|---|---|
| 1 · Oct 12 | $150,000 | $60,000 | $50,000 | $160,000 |
| 2 · Oct 19 | $160,000 | $60,000 | $50,000 | $170,000 |
| 3 · Oct 26 | $170,000 | $60,000 | $50,000 | $180,000 |
| 4 · Nov 2 | $180,000 | $60,000 | $230,000 | $10,000 |
| 5 · Nov 9 | $10,000 | $60,000 | $50,000 | $20,000 |
| 6 · Nov 16 | $20,000 | $60,000 | $50,000 | $30,000 |
| 7 · Nov 23 | $30,000 | $60,000 | $50,000 | $40,000 |
| 8 · Nov 30 | $40,000 | $60,000 | $50,000 | $50,000 |
| 9 · Dec 7 | $50,000 | $60,000 | $50,000 | $60,000 |
| 10 · Dec 14 | $60,000 | $60,000 | $50,000 | $70,000 |
| 11 · Dec 21 | $70,000 | $60,000 | $50,000 | $80,000 |
| 12 · Dec 28 | $80,000 | $60,000 | $50,000 | $90,000 |
| 13 · Jan 4 | $90,000 | $60,000 | $50,000 | $100,000 |
Each week opens on the last week's close. Replace forecasts with actuals every week and add a new week 13, so the view always runs a quarter ahead.
Common questions
When does a startup need one?
When runway is short, a large payment is coming, or a lender asks for it. It's also useful any time payroll and customer receipts don't line up.
How is it different from a runway calculation?
Runway is a monthly average. A 13-week forecast shows the timing within each month, which is where a payroll can fall short.
Does it use the direct or indirect method?
Direct: it lists actual receipts and payments, not net income adjusted for non-cash items. That's why it can show the exact week cash runs short, and why it reconciles to the bank, not the P&L.
Where it comes up
The glossary entries, founder guides and lessons on this site that use the term and link here.
- Months of cashMonths of cash is a cash and runway metric, calculated as Same as runway.Glossary
- Burn rate and runway: how to calculate them correctlyGross burn, net burn and months of runway, done the way an investor checks them: from cash, averaged, and with the hires you’ve already committed to.Guide · 3 min
- Vendor payment terms and early-pay discounts, explainedWhat Net 30 and 2/10 net 30 really mean, the annualized cost of skipping an early-pay discount, and how to schedule payment runs around your cash.Guide · 6 min
Read further
General information for US companies, not tax, legal or accounting advice. Check the specifics with a CPA before you act on them.