Cash Runway Calculator

What Is Cash Runway?

Cash runway — sometimes called cash flow runway — is how many months your business can operate before cash hits zero, given current inflows and outflows. Every business decision — hiring, marketing, expansion, fundraising — happens inside the boundary that one number sets. Companies rarely fail the day they become unprofitable; they fail the day the bank balance can't cover payroll. That's why experienced operators check runway before revenue, and why lenders and investors look at your cash line before your income statement.

Profit is an opinion. Cash is a fact.

The most common — and most dangerous — confusion in small business finance is treating profit and cash flow as the same thing. A business can show profit on paper while cash drains away through slow-paying customers, inventory buildup, loan principal payments, or growth that outruns collections. If your projection here looks worse than your P&L feels, that gap is exactly where a CFO looks first.

How to Calculate Cash Runway

The cash runway calculation rolls your cash forward month by month: start with your cash balance, add expected revenue (with growth applied after month three), subtract fixed costs and revenue-linked variable costs, and carry the balance over. Three to twelve months is the honest window for this kind of cash runway calculator — beyond that, small-business projections are guesses. Unlike a cash flow AI tool that black-boxes the math, every input and formula here is visible, so you can see exactly why the number moves.

Cash Runway Calculator: Estimate How Long Your Cash Will Last

The cash runway dashboard above turns your numbers into a month-by-month cash runway calculator: a chart of your projected balance, and a table breaking out inflows, outflows, and net change for every month. A positive average net flow means the business funds itself — the question becomes how to deploy the surplus. A negative net flow isn't automatically bad (growth usually costs money), but it puts a clock on the business: your runway. Under six months of runway means acting now — collections, cost deferrals, financing — because every fix gets more expensive as the clock runs down. Six to twelve months means you have time to fix causes rather than symptoms.

How a Fractional CFO Extends Runway

Most businesses have hidden runway. Faster invoicing and collections, renegotiated vendor terms, pricing corrections, cutting spend that isn't producing, and arranging credit lines before they're needed — a fractional CFO typically finds two to three additional months inside an existing business, without dramatic cuts. Through the US Fractional CFO Alliance you can review profiles and speak with up to five experienced CFOs, then choose who you work with — no agency fees, no markups, first introduction within two working days.

Frequently Asked Questions

What Is a Cash Runway Calculator?

A cash runway calculator projects your monthly cash balance forward using your current cash, expected revenue, and costs, showing the month your balance would hit zero if current trends continue. This tool builds that projection for 3–12 months from the numbers you enter.

How Do You Calculate Cash Runway?

Start with your cash balance, add expected monthly revenue, subtract fixed costs (payroll, rent, marketing) and variable costs (a percentage of revenue), and roll the balance forward month by month — exactly what this tool does for 3–12 months.

What Information Do I Need to Calculate Cash Runway?

Your current cash balance, expected revenue for the next few months plus a growth rate, and your fixed costs (payroll, rent, marketing, other) and variable costs — typically COGS as a percentage of revenue.

How Long Should a Startup's Cash Runway Be?

Most investors and operators look for at least 12–18 months of runway after a raise, with under six months considered a red-alert zone. Under six months means acting now on collections, cost deferrals, or financing — every fix gets more expensive as the clock runs down.

How Often Should I Recalculate My Cash Runway?

Monthly at minimum, and immediately after any material change — a new hire, a lost customer, a pricing change, or a slow month. A cash runway calculation from three months ago can be dangerously wrong if revenue or costs have shifted since.