Cash Flow Calculator
Cash position forecast.
Project ending cash and runway from starting balance, inflows, and outflows. Enter starting cash and cash inflow for an instant result.
What this tool does
This tool forecasts cash position month by month from starting cash, monthly revenue, monthly expenses, forecast period, and revenue growth rate.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Cash flow forecasting projects month-by-month what's in the bank, spotting shortfalls before they happen. Start with current cash, add monthly revenue (growing over time), subtract monthly expenses. The result shows ending cash each month and the lowest point along the way - the 'cash valley' that signals when overdraft or funding is needed.
50k starting cash with 20k monthly revenue and 22k monthly expenses burns 2k/month. Without growth, that's 24k/year burn, hitting zero in 25 months. Add 10% annual revenue growth and the business becomes cash-positive around month 12, ending year 1 at 56k.
Most small businesses fail from cash flow, not profit. A profitable business with 60-day customer payment terms and 30-day supplier terms can run out of cash while booking record revenue. This tool doesn't solve cash timing within a month, but the month-level forecast catches the bigger problem: whether you're heading toward an empty account.
Run it with sensible defaults
Using starting cash of 50,000, monthly revenue of 20,000, monthly expenses of 22,000, months to forecast of 12 months, the calculation works out to 37,311.36. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.
The levers in this calculation
The inputs — Starting Cash, Monthly Revenue, Monthly Expenses, Months to Forecast, and Revenue Growth % (annual) — do not pull with equal force. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.
How the math works
For each month: cash = cash + revenue - expenses. Revenue grows by (annual growth ÷ 12) monthly. Track lowest point and months in deficit. The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".
Using this as a check-in
Re-run this every three months. A single reading tells you where you stand; four readings tell you whether things are improving. The trend matters more than any individual snapshot.
What this doesn't capture
The score is a composite of the inputs you provide. Life context — job security, family obligations, health, housing — doesn't appear in the math but shapes the real picture. Use the number as a prompt, not a verdict.
£20,000 £ + (15,000 £-18,000 £)×12m = -$16,000.00.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Ending cash = starting + (inflow - outflow) × months. Runway = starting / |net monthly| if negative.
References
Frequently Asked Questions
Cash flow vs profit?
What's runway?
How often to forecast?
What if cash flow goes negative?
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