How do I build a 13-week cash flow forecast?
The 13-week cash flow forecast is what lenders ask for and what the monthly model can't answer: not "are we profitable in Q4" but "do we dip below the covenant in week seven." Building one in Excel means a week-by-week grid of receipts, payroll runs, rent and taxes, hand-rolled cumulative sums, and a header cell holding the opening cash that someone pasted wrong. The demo below builds the whole walk from a signed receipts/disbursements export — one question in, weekly net and projected balance out.
The cash_forecast_13w.csv sample (week_start…) is registered as a DuckDB table in your browser — the exact engine workspaces use. SQL is always shown.
Running on the sample cash_forecast_13w.csv — the question is editable, and the Your own CSV tab registers your file in your browser instead.
Sample datacash_forecast_13w.csv
How to build a 13-week cash flow forecast — without the manual grind
Signed amounts in, weekly walk out
Receipts are positive and disbursements negative in the source — the FP&A convention that makes the weekly roll-up one GROUP BY. The generated SQL pivots the export into receipts, disbursements and net per week, in order.
The projected balance line
Opening cash plus the cumulative net per week gives the projected balance for all 13 weeks — the line the bank actually reads. Payroll and tax weeks show up as visible dips instead of surprises.
Re-run it every week
In a workspace the query saves as a re-runnable artifact with a share link. Each Monday's export re-projects the quarter — the forecast rolls forward instead of being rebuilt.
Common questions
Where does the opening cash balance come from?
The sample carries it as a constant opening_cash column (the workbook convention — the value repeats on every row) and the SQL reads it with MAX(). Your export can also name it opening_balance; or drop the column and the template still produces the weekly cumulative net.
Does it work with my own categories?
Yes — the template works off signed amounts, not category names, so payroll cadence, rent, taxes and anything else in your export roll up correctly. Category-level detail stays one GROUP BY away in the SQL.
Why 13 weeks specifically?
It's one quarter of weekly visibility — long enough to catch payroll cycles, tax dates and rent, short enough that the receipts assumptions are honest. The template works for any horizon your export covers.
Run this on your own export, every month
Free workspace: 10 questions/day, files up to 10 MB. Pro $15/mo ($99/yr) for 100 MB. Your files never leave your browser.
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