Smart Budget & Cash-Flow Planner

Free Interactive Budget & Cash-Flow Planner

Most budget tools give you a number and forget about you. This one shows you the whole picture and then hands you the spreadsheet. Type in your take-home pay, your fixed bills, and your everyday spending, and the planner instantly works out four things that actually matter: your monthly surplus (what's left after everything), your savings rate (the percentage of income you keep — the single best predictor of financial progress), your projected year-end cash, and your runway (how many months your current savings would cover your expenses if your income stopped tomorrow).

How the Math Works

Each month we take your income and subtract your expenses to get net cash flow. We carry your cash balance forward month to month — this month's closing balance becomes next month's opening balance — and add interest on your savings along the way. We let income grow and expenses inflate at the small monthly rates you set, so the 12-month forecast reflects real life, not a frozen snapshot.

The interest calculation converts your annual savings rate (APY) to a monthly equivalent using the standard compounding formula: monthly rate = (1 + APY)^(1/12) − 1. Your income and expenses compound at their respective monthly growth rates, so a 0.5% monthly income growth compounds to about 6.2% over the year — which is why the 12-month picture can look meaningfully different from month 1.

How to Use the Planner

Start with the Income group on the left: enter your after-tax take-home pay, any side or business income, and passive income like rent or dividends. Then fill in Fixed Expenses (bills that don't change month to month — housing, utilities, insurance, debt payments, subscriptions) and Variable Expenses (food, transport, lifestyle, miscellaneous). Finally adjust the Plan & Growth inputs to set your starting cash, growth assumptions, and emergency fund target.

Every number updates instantly as you type — no Calculate button needed. Flip between Conservative, Base, and Optimistic scenarios to stress-test your plan. Conservative assumes slower income growth and faster cost inflation; Optimistic assumes the reverse. Switch to Custom to type any numbers you like without any overlay.

Understanding Your Results

The monthly surplus is your single most important number. A surplus above 20% of income ("Strong saver") puts you firmly on a wealth-building path. Between 10–20% ("On track") is solid. Under 10% ("Thin margin") means most of what you earn is going out the door — a small income boost or expense cut can make a big difference. A deficit means expenses exceed income and your cash is shrinking every month.

Runway tells you how many months your current savings pot would last if income stopped entirely. Many financial advisors recommend 3–6 months as a minimum emergency fund. The planner shows you both how far you are from your target and how many months of saving it will take to get there.

The 12-month cash balance chart shows whether your trajectory is rising or falling — and whether it accelerates or stabilizes toward year-end as compounding kicks in. The income vs expense bar chart makes it easy to spot if growing costs are catching up to income over the year.

Download the Real Excel Spreadsheet

Hit Download .xlsx and you get a genuine Excel workbook — not a picture of numbers, but live formulas. Open it in Excel or Google Sheets, change an assumption in the Assumptions tab, and every total recalculates inside the file. It's organized into four tabs: Assumptions (the only cells you edit), CashFlow (the 12-month engine with formulas), Dashboard (headline KPIs), and Read Me (instructions). The free download covers three months; unlock the full 12-month model — plus bonus net-worth and debt-payoff tabs — through BookBay.

Worked Example (Base Defaults)

Frequently Asked Questions