LTV to CAC calculator. Ratio, payback and CPI to CAC.
plug in your numbers to see lifetime value, your LTV to CAC ratio, how many months until a user pays back, and what your CPI really costs per paying user.
The formulas this calculator uses
everything runs in your browser. nothing is saved or sent. these are the simple versions an app founder can use today, the same ones explained in LTV to CAC ratio for apps and CPI vs CAC.
- LTV = monthly revenue per paying user × gross margin ÷ monthly churn
- LTV : CAC = LTV ÷ CAC
- payback (months) = CAC ÷ (monthly revenue per paying user × gross margin)
- CAC from CPI = CPI ÷ share of installs that become paying users
the default numbers are illustrative, not from a real account. for paid channels, run the same maths per campaign, because brand campaigns make the average look better than it is. see how to calculate Apple Ads payback.
Numbers look off? Send them to me.
share your app and the numbers you plugged in. i'll reply myself with where i think the leak is. no pitch, not a sales call.
Frequently asked questions
How do you calculate the LTV to CAC ratio for an app?
estimate lifetime value as monthly revenue per paying user, times gross margin, divided by monthly churn. then divide that by your customer acquisition cost. a subscriber paying $10 a month at 70% margin with 10% monthly churn is worth about $70, so a $35 CAC gives a 2:1 ratio.
What is a good LTV to CAC ratio?
the common rule of thumb is 3:1, which comes from SaaS. for apps, payback time matters as much as the ratio: a 3:1 ratio that takes 20 months to pay back can still run you out of cash. set the payback ceiling your runway allows, then check the ratio.
How do I turn CPI into CAC?
divide your cost per install by the share of installs that become paying users. a $2 CPI with 4% of installs paying means a $50 CAC per paying user. that gap is why an app can look cheap on CPI and still lose money on every customer.