The calculator Months of cash left
money available to the business now
everything the business spends monthly
Your runway
Your cash, month by month
The line is your cash if revenue and expenses stay where they are. Where it meets the dashed zero line, the cash balance reaches zero. Hover the chart for any month, or open the table under it.
Knowing this one number, and recomputing it monthly, is the money discipline in The One-Person AI Business: Basics →
How to read it The one number a solo operator should always know
Runway is how long your cash lasts if nothing changes. You take the money the business has right now and divide it by how much more it spends than it earns each month — the net monthly burn. The answer is a count of months: the point, at today's pace, where the account reaches zero.
It's the single most useful number for a one-person business, because it turns a vague worry ("am I going to be okay?") into a concrete deadline you can act on. Runway of eight months is a calm planning horizon. Runway of two months is a decision you needed to make last week.
The formula, in full
Net monthly burn = monthly expenses − monthly revenue. If that's positive, you're spending more than you bring in, and runway = cash on hand ÷ net monthly burn, counted in months. If revenue is at or above expenses the burn is zero or negative — there's a monthly surplus, cash isn't shrinking, and runway has no limit.
A worked example
A business holds $12,000 in cash, brings in $3,000 a month and spends $5,000. The net monthly burn is $5,000 − $3,000 = $2,000. Divide the cash by that burn: $12,000 ÷ $2,000 = 6.0 months of runway. That's the deadline. The useful move isn't to panic at month six — it's to act while there's still room, before the runway is down to around three months.
Now nudge revenue up to $6,000 against the same $5,000 of expenses. Expenses no longer exceed income, so there's no burn at all — there's a +$1,000.00/month surplus, cash is growing, and runway shows no limit.
Edge cases the calculator handles
- Revenue equal to expenses is break-even: burn is exactly zero, so there's no limit — the business isn't losing cash, but it isn't building any either.
- Revenue above expenses flips burn into a surplus, shown as a positive +amount/month, and runway reads "no limit" because the cash pile is rising, not falling.
Common questions
Is this a forecast of when I'll run out?
No — it's a snapshot at today's burn, not a prediction. Revenue and costs both move, sometimes sharply, and a single good or bad month changes the picture. Treat the runway as a reading of where you stand right now, and recompute it each month as the real numbers land.
What counts as "cash on hand" and "expenses"?
Cash on hand is money the business can actually reach now — not invoices you're owed or money that's tied up. Expenses are everything the business spends in a typical month: tools, subscriptions, fees, anything recurring. Use your own real figures, not hopeful ones, or the runway flatters you.
Is this financial advice or a guarantee?
No. It's arithmetic on numbers you enter, and it isn't financial advice. What actually happens depends on your sales, your costs, and choices this box can't see. It just gives you the single most useful number to know — and a reason to check it every month.
It's one tool from The One-Person AI Business — Basics, which takes someone from no idea to a real first sale, running the whole thing solo with AI as the team — and counting the money honestly along the way.
See the One-Person AI Business series →