What is this LTV / CAC calculator?
A free, browser-based calculator for the core unit economics of any subscription or repeat-purchase business. Enter ARPU, gross margin, churn (or a direct lifetime), and acquisition cost, and it computes lifetime value (LTV), the LTV:CAC ratio, and the payback period — the three numbers investors and founders watch most. Everything runs locally in your browser, so your data is never uploaded.
The formulas
- Customer lifetime = 1 ÷ churn rate (or entered directly).
- LTV = ARPU × gross margin × lifetime.
- LTV:CAC ratio = LTV ÷ CAC (aim for 3:1 or higher).
- Payback period = CAC ÷ (ARPU × margin).
How to use it
- Enter ARPU and gross margin for one period (e.g. monthly).
- Choose churn-based or direct lifetime, then enter that value.
- Enter your CAC and read LTV, the ratio, and payback on the right.
Common use cases
- Checking whether your acquisition spend is sustainable.
- Preparing unit-economics slides for investors or leadership.
- Setting a target CAC from a desired LTV:CAC ratio.