Cash Flow Forecaster
Forecast monthly ending cash from starting balance, inflow, outflow, and a growth rate.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this cash flow forecaster
- Enter your starting cash balance (positive or negative).
- Enter your monthly inflow — receipts, revenue, or income coming in each month.
- Enter your monthly outflow — payroll, rent, suppliers, anything going out.
- Pick how many months to project (1–240).
- Optionally enter a monthly growth rate that compounds inflow and outflow each month.
- Choose your currency and press Calculate to see the full monthly table and the ending balance.
- Use Copy to save the headline figures or Reset to start over.
About this cash flow forecaster
The cash flow forecaster projects how your cash balance evolves month by month from a starting balance, a monthly inflow, a monthly outflow, and an optional growth rate that scales both flows each month. It flags the first month the balance goes negative.
The formula is: for each month m from 1 to N, inflow_m = inflow × (1 + g)^(m−1), outflow_m = outflow × (1 + g)^(m−1), net_m = inflow_m − outflow_m, ending_m = ending_{m−1} + net_m, with ending_0 = starting_cash. Totals at the bottom sum inflow_m and outflow_m across the horizon.
Worked example: starting cash 50,000, monthly inflow 12,000, monthly outflow 9,000, 12 months, growth 0%. Each month net is 3,000, so ending cash after 12 months = 50,000 + 36,000 = 86,000. Total inflow 144,000, total outflow 108,000, net change 36,000.
This is a forecast, not a guarantee. Real cash flow is bumpy — seasonality, one-off purchases, customer payment delays, and tax timing all break the constant-growth assumption. Use the result to test assumptions and stress-test runway, not as a guarantee of solvency. Not financial advice.
FAQ
- What does the growth rate apply to?
- It applies equally to both inflow and outflow each month, compounded. Use it to model a business where both revenue and costs grow at roughly the same rate; if revenue and costs diverge, run two scenarios with different growth rates and compare ending balances.
- What does the “cash goes negative at month X” warning mean?
- It is the first month where the ending balance drops below zero. That is your runway under the given assumptions. If the warning never appears, you stay cash-positive for the whole horizon.
- Why are only the first 12 and last 12 months shown for long forecasts?
- Long tables (more than 24 months) are easier to scan if you see the start and the end. The full ending balance and totals at the bottom are always calculated from every month, not just the visible rows.
- Can starting cash be negative?
- Yes. Use a negative number if you start the horizon already overdrawn, for example with a line of credit drawn down. The math is the same.
- Why is there a 240-month cap?
- Beyond 20 years a constant growth rate is unrealistic, and the table becomes unwieldy. Build a new forecast for each strategic phase instead of one very long projection.
- Is anything stored or sent to a server?
- No. All calculation runs in your browser; nothing is sent or saved. Closing the page clears every input.