How long can your startup keep breathing?

What this simulator covers

In one sentence

It projects how long your cash lasts and whether your monthly revenue grows past your monthly expenses before the balance hits zero.

What you enter

Five monthly figures: cash on hand, current monthly revenue (MRR), monthly expenses, monthly growth rate and monthly churn rate. Amounts are in USD and are treated as averages, not as a month-by-month budget.

What you get

Months of runway, the first month your revenue covers that month's expenses, how this month's revenue and expenses compare, a cash trajectory chart of up to 36 months, what it would take to break even today, and a one-line summary you can share.

Assumptions and exclusions

• Revenue compounds each month by growth minus churn, starting from the MRR you enter. The two rates are combined into a single net rate rather than modelled separately.
• Expenses stay flat for every month, and each month's revenue is earned before that month's expenses are paid. The revenue a month uses is the run rate carried in from the end of the month before; growth is applied again at that month's end.
• Runway is the first month the balance reaches zero or below, counted in whole months.
• Break-even is the first month whose own cash flow stops being negative, meaning the revenue that month uses reaches your expenses. It is counted in whole months. “Already there” means the MRR you entered already covers your expenses; a month number means the projected balance stops falling in that month and does not fall again. Covering expenses today is not the same as staying covered: when churn outruns growth, revenue shrinks back below expenses, and “Already there, but cash runs out” means the balance still reaches zero inside the same 1,200-month cap.
• Break-even can land after the balance has already reached zero, and the month it lands in is still shown, marked “after empty”. The model keeps running past a zero balance, so that number describes the revenue curve, not a path you could fund without raising more cash. “Not within 100 years” means revenue never reaches expenses inside the same 1,200-month cap, whether or not the balance runs out first.
• “Current monthly burn” is a month-1 figure: the expenses you enter minus the MRR you enter, before either rate is applied. A surplus there does not mean the balance survives, so when cash still reaches zero the stat reads “for now” and the levers below say the surplus does not stop it rather than repeating it as advice. “Even” means the gap between the MRR and expenses you entered rounds to $0, which is neither a burn nor a surplus. Amounts here are rounded to whole dollars, so such a gap would otherwise be reported as a $0 burn or a $0 surplus.
• Taxes, fundraising, debt and financing, one-time costs, hiring plans and payment timing are all excluded.
• “Sustainable trajectory” means cash stays positive across a simulation capped at 1,200 months, or 100 years. It is a statement about the model, not a prediction.

Data source and date

None. Every figure in the forecast is derived from the five numbers you type in. The simulator loads no market data, benchmarks or external rates, so there is nothing here to go out of date.

Privacy

• The whole simulation runs in your browser. tiny-tools has no backend, so your figures are never sent anywhere to be computed, and they are gone when you reload the page.
• Anonymous product analytics go to PostHog: that the simulator was viewed, started, completed and shared, whether sharing used the system share sheet or the clipboard, and the hostname of the site that linked you here. Your cash, revenue, expense and rate inputs are not included in those events.
• Your IP address reaches PostHog, which is configured to derive a country and time zone from it and then discard it rather than store it on the events.
• Sharing is yours to direct. The summary text contains your runway and break-even months, and it goes only to the app or clipboard you pick.
• Session replay is part of the same analytics setup, so your on-screen session can be recorded. Input masking is applied by a PostHog project setting rather than by anything on this page, and values rendered on the page, including the forecast, can appear in a recording either way.
• PostHog stores an anonymous visitor identifier in this browser. Nothing else about your scenario is saved on this device.