How to make a cash flow forecast (and what one actually costs to have built)
A cash flow forecast is a month-by-month table of money in and money out, with your assumptions kept on their own tab so changing one figure moves the whole year. The part that separates a working model from a tidy-looking grid is whether the monthly cells contain formulas pointing back at those assumptions, or numbers somebody calculated once and pasted in. You cannot tell the difference from a screenshot. Below is a real one, produced in ninety seconds, with the file attached so you can open the cells yourself.
How to do it
- Separate the assumptions from the arithmetic Put every figure you might argue about — rent, ingredient cost, wage rate, card fee percentage, the December bump — on its own sheet. Everything on the cash flow sheet should refer back to it rather than restate it.
- Write the months as formulas, not values Each monthly cell should compute from the assumptions tab. This is the step that decides whether the model is usable next quarter or has to be rebuilt.
- Test it by breaking one number Change a single assumption and watch the twelve months move. If a cell does not move, it was typed rather than calculated — that is the defect a screenshot cannot show you.
- Check the seasonal months separately December, or whatever your peak is, is where a flat model quietly lies to you. Make sure the bump is an assumption you can dial, not a hard-coded exception.
The exact request
I'm opening a small neighbourhood bakery next spring. Build me a 12-month cash-flow spreadsheet I can actually edit: monthly rows for rent, flour and butter, wages, utilities, card fees, and a seasonality bump for December. Put my assumptions on their own tab so I can change one number and watch the year update. Give me the .xlsx.
What came back
What it cost
| Cash-flow model run | $0.375 |
| Total | $0.375 |
What it got wrong
- Not every formula reaches the assumptions tab: 86 of the file's 154 formulas do. Before you rely on it, click the figures that matter most to you and check they trace back rather than being typed in.
- The numbers in it are the ones from the request above, not yours. It is a working model with a worked example inside it, and swapping in your own figures is the first thing you should do.
- It is a forecast, not an accounting record. Nothing in it reconciles against a bank feed.
Questions people ask
What should a cash flow forecast include?
Monthly rows for each recurring cost and each revenue line, a separate assumptions sheet, and a seasonality adjustment for whichever months are not typical. The version below uses rent, ingredients, wages, utilities and card fees because that was the business in the request; the structure is the reusable part, not the categories.
How much does it cost to have one built?
This one cost $0.375 and took about ninety seconds, on the Smart tier. The receipt is on this page. There is no plan to buy first, so a month you build nothing costs nothing.
Opens with this request already filled in. You pay for the run, not a plan.