About the Cash Flow Calculator
This cash flow calculator projects your business bank balance month by month. Start with the cash you have today, enter typical monthly revenue collected and monthly expenses paid, and set how fast each is expected to grow. The forecast shows your ending cash, total inflows and outflows, and the lowest point your balance reaches along the way.
It is designed for founders, freelancers and small-business owners who need a quick cash forecast for a bank meeting, a hiring decision or a seasonal slowdown. A business can be profitable on paper and still run out of cash, so watching the lowest balance and the first month you would go negative matters more than the average.
The model treats revenue as cash actually received and expenses as cash actually paid, with growth compounding monthly from the first month. For lumpy items like annual insurance, tax payments or loan draws, add them to a month-by-month spreadsheet after using this as a baseline.
With the default inputs, the ending cash balance is $105,785.67. Change any value above to recalculate instantly.
How to use the cash flow calculator
- 1Enter the cash you have in the bank today.
- 2Enter the cash you expect to collect next month and how fast it will grow.
- 3Enter monthly cash outflows and their expected growth.
- 4Choose how many months to project.
- 5Check the ending balance, the lowest point and the monthly table for shortfalls.
Formula and method
Each month the calculator grows the first-month inflow and outflow by their monthly growth rates, subtracts outflows from inflows to get net cash flow, and adds the result to the previous month’s ending balance. The ending cash balance is the starting balance plus the sum of all monthly net cash flows.
The lowest cash balance is the minimum month-end balance across the forecast, including the starting balance. Growth compounds monthly, so 3% a month is roughly 42.6% over a year. Figures are cash, not accounting profit: use the money you actually collect and pay, not invoices raised or bills received.
- I₀
- Month-1 cash inflows
- O₀
- Month-1 cash outflows
- g, gₑ
- Monthly growth rates for inflows and outflows
- m
- Month number (1, 2, 3…)
Worked examples
Growing agency, 12-month forecast
Inflows start at $25,000 and grow 3% a month while outflows start at $22,000 and grow 1%. Over 12 months that is about $354,801 in and $279,015 out, lifting cash from $30,000 to about $105,786.
Monthly loss burns through cash
Losing $3,000 every month drains the $10,000 starting balance, which goes negative in month 4 and ends at −$8,000 after six months. The business would need at least $8,000 more to get through the period.
Dip before growth catches up, 24 months
Expenses start $5,000 above inflows, so cash falls for eight months to a low of about $26,955. Because inflows grow faster (2% vs 0.5% a month), cash recovers and ends two years later at about $122,437.
Frequently asked questions
What is the difference between cash flow and profit?+
Profit counts revenue when it is earned and expenses when they are incurred, even if no cash has moved. Cash flow tracks money actually received and paid. A business with slow-paying customers can be profitable yet run out of cash.
What is a cash flow forecast used for?+
A forecast shows whether you will have enough cash to pay bills, payroll and loans in each coming month. Lenders often ask for one, and it helps you time hiring, inventory purchases or fundraising before a shortfall hits.
How do I calculate monthly net cash flow?+
Subtract total cash paid out in the month from total cash received in the month. Add that net figure to the opening balance to get the closing balance, which becomes next month’s opening balance.
How much cash reserve should a small business keep?+
A common rule of thumb is three to six months of operating expenses, more for seasonal or project-based businesses. Use the lowest cash balance in this forecast to see how close you come to that buffer.
What is the difference between operating, investing and financing cash flow?+
Operating cash flow comes from day-to-day sales and expenses, investing cash flow from buying or selling assets like equipment, and financing cash flow from loans, repayments and owner investment. This calculator combines them into one monthly figure.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.