Cash
Bank balance you can spend today (operating cash, not locked equity).
Tool 06
Runway & burn.
How many months until cash hits zero — without a spreadsheet. Optional revenue growth so you can see if the curve bends before you run out.
Burn
Expenses minus revenue each month. Positive burn means cash is shrinking.
Runway
Months until cash hits zero on this model — your countdown.
Growth
Optional monthly revenue growth %. Expenses stay flat in this napkin model.
Example
$100k cash, $5k revenue, $12k expenses, 5% monthly growth: net burn starts at $7k/mo and shrinks as revenue climbs — runway is longer than the flat-burn napkin ($100k ÷ $7k ≈ 14 months).
Is this accounting-grade?
No. It’s a founder napkin: flat expenses, simple growth, no tax timing, no receivables lag. Use it to decide “raise / cut / wait,” not for your board pack.
What if I’m already profitable?
If revenue ≥ expenses (and growth isn’t deeply negative), you’ll see “no zero-cash date” — you’re not burning down on this model.
Why cap at 120 months?
Beyond ~10 years the napkin is fiction. If you’re still cash-positive that far while burning, we show 120+ instead of a fake exact date.