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How to Calculate Cash Runway for Your Business (Step by Step)

Cash runway = Cash on hand ÷ Monthly operating expenses.

That formula gives you the number of months your business can continue operating at its current cost structure before the bank account reaches zero. It is the single most important number a service founder can calculate, and most never do because monthly revenue keeps arriving and the question never feels urgent until it is.

The basic formula and what each input means

Cash on hand is the actual balance in your business bank account right now. Not projected revenue. Not invoices outstanding. Not money a client promised to send next week. The number that would appear if you logged into your bank account at this moment.

Monthly operating expenses include every recurring cost the business incurs whether or not a single hour of client work is delivered: rent or coworking fees, software subscriptions, insurance, contractor retainers, loan payments, and the founder's own draw or salary. If the business stopped generating revenue today, these costs would continue.

A consultant with $21,000 in the bank and $7,000 in monthly operating expenses has a cash runway of 3 months. That means the business could absorb a complete revenue stoppage for 90 days before reaching zero.

Why the basic formula misleads service founders

The formula above works cleanly for businesses with predictable, recurring expenses and a clear distinction between revenue and cash. Most service businesses have neither.

Three adjustments make the calculation accurate for a consulting or professional services firm.

Adjustment 1: Account for variable revenue months. Service businesses rarely have identical revenue month to month. A consultant earning $28,000 in April might earn $19,000 in May because of a client pause, a lighter project load, or a gap between engagements. The basic runway formula assumes revenue drops to zero, but a more useful version incorporates average monthly revenue shortfall: the difference between average monthly revenue and average monthly expenses over the trailing three months. This tells the founder how long the business can sustain its current gap between income and cost, not just how long it can survive without any income at all.

Adjustment 2: Factor in delayed receivables. A consultant who invoices $12,000 today but operates on net-30 terms with two clients and net-45 terms with a third does not have $12,000 in cash. The cash arrives 30 to 45 days after invoicing, which means the runway calculation needs to subtract outstanding receivables from available cash and add them to a future period. A founder who sees $35,000 in the bank but has $14,000 in unpaid invoices beyond 30 days has an effective cash position that is significantly different from what the bank balance suggests.

Adjustment 3: Include seasonal client pauses. Many service businesses experience predictable slowdowns during specific months (August, late December, early January). If a consultant's two largest clients historically pause for two to three weeks during the same period, the runway calculation should model what happens to the cash position during that overlap. A business with 4 months of runway in October may drop to 2.1 months of runway by mid-January if two clients pause simultaneously and expenses continue.

The five runway positions

Once the calculation is complete, the resulting number maps to one of five operating positions. Each position carries a specific set of decision rules.

Critical: under 1 month. The business cannot absorb a single client pause, late payment, or unexpected expense. Every decision is a survival decision. No discretionary spending. No new tools, no conferences, no rate discounts to win new work. The only priority is cash collection and pipeline acceleration.

Exposed: 1 to 2 months. One slow month becomes a crisis. The business is operating without a meaningful buffer, and any disruption to the top one or two clients creates immediate financial pressure. No new commitments that do not generate revenue within 30 days.

Fragile: 2 to 3 months. The business has a thin buffer but no structural protection. A client departure or a two-week gap between engagements is manageable, but a second disruption in the same quarter is not. Operate defensively: no rate discounting, no speculative projects, no hiring.

Baseline: 3 to 6 months. The business can absorb a single disruption without changing its operating cadence. Normal operations are sustainable. The priority at this level is building toward Structured through consistent margin management and scope discipline.

Structured: 6 or more months. The business can negotiate from strength. Rate increases, client exits, strategic pauses, and hiring decisions can be made without financial pressure dictating the timeline. This is the operating position where long-term growth decisions become possible.

Most service founders generating $15,000 to $50,000 per month land in the Fragile or Exposed range when they first run the calculation. The number is rarely where they expect it to be, because the bank balance creates an illusion of stability that the runway calculation corrects.

Running the calculation in 60 seconds

The Cash Runway Calculator asks for two inputs: cash on hand and monthly operating expenses. It returns your runway in months, your position (Critical through Structured), and a plain-language interpretation of what that position means for your next set of decisions.

Free. No email required. Runs in your browser.

For founders who want to model scenarios (what happens if Client A pauses, what happens if expenses increase by $2,000, what happens if receivables are delayed by two weeks), the calculator supports multiple scenario inputs so the runway number reflects real conditions rather than a single static snapshot.

Frequently asked questions

What is a good cash runway for a small business? For a service business generating $15,000 to $75,000 per month, a minimum of 3 months of runway (the Baseline position) provides enough buffer to absorb a single client disruption without entering a crisis state. The target operating position is 6 or more months (Structured), which enables strategic decision-making without financial pressure.

How many months of runway should a consulting business have? The benchmark depends on revenue concentration. A consultant with 5 or more clients of roughly equal size can operate safely at 3 to 4 months of runway. A consultant where a single client represents 40 percent or more of revenue should target 5 to 6 months because the impact of losing that client is proportionally larger.

How is cash runway different from cash flow? Cash flow measures the movement of money in and out of the business during a specific period. Cash runway measures how long the business can continue operating at its current cost structure before running out of money. A business can have positive cash flow in a given month and still have a dangerously short runway if the cash balance is low relative to expenses. The two numbers answer different questions: cash flow tells you about this month, and runway tells you about the months ahead.

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