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When does your cash run out? Three numbers give the month.
Enter your cash balance, monthly spend and monthly revenue. The Runway Calculator returns your net burn and your runway in months. Free to use.
Spend minus revenue
Runway
6.0 mo
Out of cash around April 2027
Raise-by date (6 months before)
0.0 mo
Rounds take about six months end to end
The date you stop being able to pay people
You know roughly what is in the bank. You do not know the month it hits zero. The number lives in someone's head or in a tab nobody opens, and it gets worked out in a panic the week before payroll.
What you enter and the month you get back
Cash balance.
What is in the bank today.
Monthly spend.
Everything that leaves each month.
Monthly revenue.
The revenue you collect each month.
Result.
Net burn and runway in months.
Net burn = monthly spend − monthly revenue. Runway = cash ÷ net burn. If revenue covers spend, you are not burning, and there is no run-out month. Otherwise, count that many months forward from today and you have the month the cash runs out. New money has to close before it.
Worked example: six months, then eight, then 13.5
Assumptions: spend and revenue stay flat every month, and no money comes in other than revenue.
Cash:
$240,000. Spend: $60,000 a month. Revenue: $20,000 a month.
Net burn:
$60,000 − $20,000 = $40,000 a month
Runway:
$240,000 ÷ $40,000 = 6 months. Six months from today, the bank account reaches zero.
Revenue rises to $30,000.
Net burn:
$60,000 − $30,000 = $30,000
Runway:
$240,000 ÷ $30,000 = 8 months
Revenue stays at $20,000 and you close $300,000.
Cash:
$240,000 + $300,000 = $540,000
Runway:
$540,000 ÷ $40,000 = 13.5 months
An extra $10,000 of monthly revenue buys 2 months. Start the raise while the runway is still longer than the time a raise takes.
A starting point, not a forecast. Spend and revenue rarely stay flat.
Where the Runway Calculator stops
- It holds spend and revenue flat. Hiring plans and growth change the answer.
- It does not tell you how much to raise. The fundraising target in BildrX Financial Tools does.
- It does not show what the raise costs you in ownership. The Dilution Calculator does.
Save the scenarios and test the raise on your cap table
BildrX Financial Tools saves runway and burn as scenarios, works out your fundraising target, and tells you whether you are default alive or default dead. Test what that raise costs in dilution in the priced-round sandbox, then record the round on your cap table. Import your spreadsheet and the cap table is live in under 30 minutes.