How do I forecast cash flow and see how long my cash will last?
Short answer: Start with the cash you have today. List the money you expect in and out each month, subtract to get net cash flow, and carry the balance forward. Runway is how many months the balance lasts at the current rate of net outflow. A spreadsheet works; SmartCash does the same job in a web app, from $9.99 a month.
Written by JMS Dev Lab, the maker of SmartCash. Facts checked against the SmartCash billing code and live site on 3 November 2026.
The steps
- Start with cash available. The money you can actually spend today, not profit.
- List money in. Sales and other income, by month, when the cash arrives rather than when you invoice.
- List money out. Stock, wages, rent, tax and loan payments, including the lumpy ones that fall in one month.
- Subtract to get net cash flow for each month and carry the balance forward.
- Check runway. If net cash flow is negative, divide your cash available by the average monthly shortfall. That is roughly how many months you have.
- Test a downside. Run it again with lower sales or a bigger bill to see how thin the margin gets.
Where SmartCash fits
- You add income and spending by hand, paste a list, or import a CSV file with column mapping.
- The dashboard shows cash available, money in, money out and how long your cash will last.
- The forecast looks six months ahead and names the method it used. It starts with trend extrapolation and moves to an ARIMA model with a 95% range once you have 20 months of history.
- What-if scenarios let you test a decision before you make it.
- Reports (PDF, Excel, CSV or JSON depending on the report) can be sent to your accountant.
The dashboard and cash runway are on every plan. The forecast and what-if scenarios start on Professional.
What SmartCash does not do
- It does not connect to your bank or ask for bank passwords, so you record or import the figures yourself.
- It does not give financial or tax advice, file tax returns or replace your accountant.
Which one fits
If you are comfortable in a spreadsheet and your cash picture is simple, a spreadsheet is enough. If you want your forecast to pull straight from accounting software such as QuickBooks or Xero, look at a tool built around that sync; SmartCash does not have one. If you want a ready-made forecast, runway and scenarios from figures you enter or import, without building the model yourself, SmartCash fits.
Questions
How far ahead does the forecast go?
Six months, month by month.
How accurate is it?
A forecast is only as good as the records and the method. SmartCash tells you which method it used, and shows backtest accuracy only when there is enough history.
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