A 13-week forecast looks one quarter ahead, one week at a time. It is short enough to be accurate and long enough to see trouble coming. It also happens to be one of the fastest ways to make better hiring and spending decisions.
Set it up
- Start with today's real bank balance — not the ledger balance, the actual one.
- Make thirteen weekly columns.
- List cash in: customer payments by expected week, not invoice date.
- List cash out: payroll, rent, contractors, tax payments, software, and known one-offs.
- Roll the balance forward: opening + in − out = closing, week after week.
Be honest about timing
The forecast is only as good as your collection assumptions. If a customer "pays in 30 days" but historically pays in 47, use 47. Optimism is the most common way these forecasts fail.
A forecast you trust is worth more than a model you admire.
Update it weekly
Every Monday, replace last week's forecast with what actually happened and slide the window forward one week. Ten minutes of upkeep keeps the view current, and after a month you will see exactly where your assumptions run hot or cold.
Use it to decide
Before a hire, a lease, or a big purchase, add it to the forecast and look at the lowest closing balance in the next thirteen weeks. If it stays comfortably above your buffer, go ahead. If not, you have found the conversation to have first.