Beaconshire Advisory · www.beaconshireadvisory.com · 13-Week Cash Flow Forecast & Cash Runway Calculator · printed
Calculator · Operations
How many weeks of cash do I have — and which week is the dangerous one?
The 13-week cash forecast is the first artifact a CFO builds for a new client. Enter your recurring inflows and outflows once, drop one-off items into the week they land, and the calculator shows closing cash every week, the low point, your runway, and the week to worry about. Export it, then update it every Monday.
Closing cash by week
The dashed line is your buffer. Anything below it is a week to manage actively.
The 13-week grid
Type one-off items directly into the Extra inflow and Extra outflow columns — a big customer payment, a tax bill, an equipment purchase, an insurance renewal. Everything recalculates as you type.
Inflows vs. outflows
Where the heavy weeks are.
What this means
What a CFO would say about this forecast.
Your inputs are encoded in the page link so you can save or share a scenario. Nothing is stored on our servers.
How it works
Methodology & assumptions
- Weeks run seven days from the start date you choose (default: next Monday). Each week:
closing = opening + inflows − outflows. - Recurring items are placed by calendar: payroll on its actual run dates for the frequency you pick (weekly / biweekly from the next payroll date; semimonthly on the 15th and month-end; monthly on month-end); rent, loans, fixed costs and owner draws on the day of month you enter; estimated taxes on the federal due dates when enabled.
- One-off items from the grid are added to the week you place them in. The grid is part of the form, so they are saved in the shareable link and the CSV.
- Weeks of cash on hand = opening cash ÷ average weekly outflow. Runway (shown when average net is negative) = opening cash ÷ average weekly burn. Lowest point is the minimum closing balance across the 13 weeks.
- Why 13 weeks. Long enough to see the next quarter-end and tax date, short enough that the assumptions are still defensible. It is the standard horizon used by turnaround advisors and lenders.
- Not modeled. Credit-line draws and repayments, AR aging (enter expected collections, not invoices), sales tax remittances, and seasonality beyond what you type into the grid. For a full workbook with reconciliation and scenarios, download the 13-Week Cash Flow Command Center.
This calculator is an educational estimate built from published figures and the assumptions listed above. It is not tax, legal, or financial advice, does not account for every provision that may apply to you, and is not a substitute for a return prepared from your actual records. Figures are checked when published and may lag mid-year changes.
Questions
Common questions
How often should I update this?
Weekly, ideally Monday morning with the bank balance in front of you. Replace week 1’s forecast with what actually happened, move the start date forward seven days, and re-check the one-off grid. After a few cycles you will know your real collections pattern, which is the number most owners get wrong.
Collections or sales — which do I enter?
Collections: cash that hits the bank. If you invoice on 30-day terms, this week’s deposits come from last month’s sales. If you want to model a specific large invoice, put its expected payment date in the grid rather than inflating the weekly average.
Why does the forecast show a three-payroll month?
Because biweekly payroll produces 26 runs a year, and two months in every year contain three. Monthly budgets smooth that out; the bank account does not. The 13-week view places each run on its date so the heavy week is visible in advance.
What do I do if the forecast goes negative?
Work the levers in this order: accelerate collections (deposits, progress billing, a courtesy call on the largest receivable), defer discretionary outflows out of the low week, negotiate timing with vendors, then financing. Knowing the week and the amount three weeks ahead is what turns a crisis into a phone call.
Is this the same as the downloadable Cash Flow Command Center?
Same method, lighter tool. The Excel workbook on the Business Tools page adds bank reconciliation, base/best/worst scenarios and a KPI dashboard. Use this page for a quick read; use the workbook when you want it to live in your monthly close.
Keep going
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Want this maintained for you every week?
A rolling 13-week forecast tied to your bank feeds is the first deliverable in most CFO Advisory engagements. Retained engagements start at $750 a month.
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