SaaS calculators
Focused tools for one question at a time, when the full simulator is more model than you need. Each asks for a handful of numbers and computes the answer in your browser.
These are not simplified re-implementations. Each one drives the same sixty-month projection engine that powers the simulator, so a runway figure here and a runway figure there cannot disagree. The difference is only how many assumptions you are asked to supply: the calculators fill in the rest with documented defaults, and every page states which ones and why that matters.
That distinction is worth more than it sounds. Most calculators of this kind apply a single formula to a single month and present the result as a projection. Dividing cash by this month's burn assumes burn never changes; multiplying monthly churn by twelve overstates annual churn, and the error grows with the rate. Where the shortcut and the projection disagree, these pages show you both numbers and explain which one to plan around.
Nothing you type is transmitted or stored. Written and maintained by Assaf Schwartz, with the method behind every figure set out on the methodology page.
- Cash & capital
Cash runway calculator
Most runway calculators divide cash by last month's burn and assume burn never changes. This one projects sixty months with growth, churn and cost inflation compounding, and shows you both numbers side by side.
Open the calculator - Unit economics
LTV, CAC and payback calculator
Lifetime value, the LTV:CAC ratio and the payback period from four inputs, with the churn sensitivity that decides all three. Gross margin included, because revenue you never keep is not value.
Open the calculator - Retention
Churn and retention calculator
Convert monthly churn to annual retention properly, see how much of a cohort survives, and find the revenue ceiling your current churn rate imposes no matter how well sales performs.
Open the calculator - Build vs. buy
Build vs. buy calculator
Compare a per-seat licence against building the same thing internally over sixty months, including the maintenance engineers the business case always forgets. Includes the seat count where the answer flips.
Open the calculator - Growth vs. profit
Rule of 40 calculator
Growth rate plus profit margin, scored against the benchmark, with what it would take to reach 40 from where you are. Includes the four very different companies that all score exactly 40.
Open the calculator
Which one answers your question
“How long do we have?” is the runway calculator, but read the minimum-cash figure rather than the runway figure. Runway tells you when the money is gone; minimum cash tells you how much you actually needed and in which month the plan is tightest. For a company that eventually turns profitable those are different questions, and only the second one prices a raise.
“Are we paying too much for customers?” needs both outputs of the LTV and CAC tool. The ratio says whether a customer is worth acquiring at all; the payback period says how long you finance them before finding out. A business can clear the three-to-one benchmark comfortably and still run out of cash, because the ratio has no time in it.
“Why has growth stalled?” is usually the churn calculator, and specifically the revenue ceiling it computes. If you add roughly the same amount of new revenue each month, your recurring revenue does not grow indefinitely. It converges on new business divided by churn, and a company approaching that line will stall regardless of how well sales performs. Almost nobody is told this number before they hit it.
“Should we build this ourselves?” is the build-versus-buy tool, and the answer usually turns on the maintenance engineers rather than the build estimate everyone is arguing about. The tool reports the seat count at which the two paths cross, which settles most of these arguments before the estimate is even discussed.
“How will an investor read this?” is the Rule of 40, with the caveat that it is a statement about acceptable trade-offs rather than a target to optimise, and that four very different companies can score exactly forty. It is also the wrong measure below roughly ten million of annual recurring revenue, where a single hire can move the score by fifteen points.
Need everything at once?
The simulator models recurring revenue, engineering payroll, cloud spend and licence costs together, with break-even, runway and unit economics recalculating as you move any assumption.
Open the simulatorWant the reasoning?
Every metric these tools compute has a guide behind it explaining where it misleads, and a glossary entry giving the formula in one line.