Drop in your cash on hand and monthly net burn — the calculator tells you how many months until the bank account hits zero. Under three months is an emergency. Six to twelve is comfortable. Re-run it every time burn or revenue changes; founders who track this monthly outlive founders who don't.
Your numbers
Bank account balance today. Don't include money you haven't received yet.
Cash out minus cash in. Use the worst recent month, not the best.
The verdict
Zero around Jan 2027
Healthy. Focus on conversion and unit economics — not on raising. Buyers > investors at this stage.
How this is calculated
Runway (months) = cash_on_hand / monthly_net_burn.
Net burn = total cash out − total cash in. Net, not gross — gross burn double-counts the runway your revenue is already covering.
The "zero around …" date assumes burn stays flat. In practice burn drifts up as you hire and down as revenue grows; re-run the calc monthly with the latest bank balance.
Verdict thresholds are calibrated against the typical fundraise cycle: 3-6 months from first investor coffee to wire is normal, so under 3 months of runway means you are not raising — you are closing.
What this doesn't tell you
- Whether your burn is the right shape. $20K/month split 80% engineering / 20% distribution is different from 80% paid acquisition / 20% engineering. Two startups with the same runway can have very different odds.
- Whether you can raise. Runway tells you the deadline. Whether investors will fund you at this stage depends on traction, team, and market — none of which this calc measures.
- Whether to cut. Cutting burn extends runway but slows growth. The right move depends on whether you are pre-PMF (cut hard) or post-PMF (lean in).
Use this with
The Lean Startup
Eric Ries's Lean Startup, stripped of consultant fluff. Validated learning, Build-Measure-Learn, MVP, pivot or persevere. What it means and where it gets misapplied.
Pricing Validation
Most founders pick a price by looking at competitors and shaving 20%. That's not pricing strategy, it's matching. Real pricing validation produces a price you can defend against your own ego and your buyer's pushback.
How long does startup validation take?
Two to four weeks of focused work for a single idea. Stage 1 (market verdict) takes a day. Stages 2-3 (buyer + pain) take a week of interviews. Stage 4 (positioning) takes two days. Stage 5 (V1 scope) takes a day. Stages 6-7 (pricing + behavioral evidence) take 1-2 weeks because you need 20+ buyers and a Fake Door Test running. ShipFit compresses the decision time to 30-60 minutes; the gating work is the human conversations between stages.
Frequently asked questions
What counts as 'burn'?
Should I include money I haven't raised yet?
I'm bootstrapped with no monthly burn. Does this apply?
Why is 3 months the panic line?
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