Business Runway Calculator: How Long Cash Lasts

What this calculator can help you understand

Your net monthly burn.
How many months of runway your cash gives you.
The month cash would run out at today’s pace.
How much cutting costs or growing revenue would extend it.

When it’s useful

Every month, as part of reviewing your finances.
Before hiring or signing a lease.
When planning a fundraise or loan.
When revenue drops unexpectedly.

Who it’s for

Founders of early-stage companies.
Small business owners who aren’t yet profitable.
Freelancers building a business from savings.

What to enter

Input	What it means	Where to find it
Cash in the bank	Cash the business can use now	Business bank balances
Monthly revenue	Cash collected from customers each month	Bank deposits, not invoices
Monthly operating costs	Everything you spend running the business, except your own pay	Your bank and card statements
What you pay yourself per month	Your draw or salary	Your payroll or transfers
Revenue growth per month	How fast revenue is growing; optional	Recent months’ revenue

How to use it

Enter your business’s cash balance.
Enter your average monthly revenue and operating costs, using recent months.
Enter what you pay yourself.
Optionally, enter monthly revenue growth.
Read your burn, runway and the month cash would run out.

Understanding your results

Net burn = operating costs + your pay − revenue.
Runway = cash ÷ net burn, when revenue is flat.
With revenue growth, revenue rises each month and burn shrinks, so runway is calculated month by month.
Cost cut that doubles runway is half your current burn.

A worked example

Suppose your business has $120,000 in cash, collects $15,000 a month, spends $22,000 a month to operate, and pays you $5,000.

Net burn: $12,000 a month.
Runway: 10 months.
Doubling it: cutting $6,000 a month from costs, or adding that much revenue, would extend runway to 1 year, 8 months.
A smaller change: growing revenue to $18,000 a month would extend runway to 1 year, 1 month.
What it means: with under a year of runway, now is the time to plan, not when the bank balance is low.

Common mistakes

Using invoices instead of cash collected.
Using a single unusual month. Average several months.
Forgetting yearly or quarterly bills, such as taxes and insurance.
Counting credit lines as cash.
Assuming growth that hasn’t happened yet.

What to do with your result

Recalculate every month and watch the trend.
See how many sales would cover your costs with the break-even calculator.
Check your pricing with the profit margin calculator.

Limitations to keep in mind

The calculator uses steady monthly figures, with optional steady revenue growth. It doesn’t include taxes, loan repayments, seasonality, one-time costs or money you might raise. This isn’t accounting, legal or financial advice.

Frequently asked questions

What is burn rate?

How much more cash leaves the business each month than comes in. Gross burn is total spending; net burn subtracts revenue. This calculator uses net burn, which determines runway.

How much runway should a business have?

There’s no fixed rule, but raising money or cutting costs takes months, so it’s wise to act long before cash gets low. Many startups aim for 12 to 18 months or more after raising money.

Should I include my own salary?

Yes. If you need to pay yourself, it’s a real cost to the business. The calculator keeps it separate so you can see its effect.

How does revenue growth change runway?

Growing revenue lowers burn each month. If it grows fast enough, the business can reach breakeven before cash runs out.

What counts as cash?

Money the business can use now: checking, savings and money market balances. Unpaid invoices and unused credit lines aren’t cash until you collect or draw them.

How is this different from a personal emergency fund?

The idea is similar: months of costs covered by cash. For a household, the emergency fund calculator covers personal expenses.

Business runway calculator: how many months your cash can carry you