A free trial is only as good as the share of people who pay at the end of it. This calculator turns trial numbers into the figures that matter for planning: how many paying customers and how much new MRR a month of trials produces, what each paying customer really cost to acquire, and how many trials, or how much better a conversion rate, you need to reach a revenue goal.
How it works
New paying customers = trial sign-ups × conversion rate. New MRR = new customers × monthly price, and new ARR is that figure × 12.
Acquisition cost per paying customer = cost per trial ÷ conversion rate. If a trial costs $20 and 15% convert, each paying customer cost $20 ÷ 0.15 = $133.33, because you paid for the trials that didn't convert too.
Revenue per trial = conversion rate × price. It is the most useful single number for comparing channels: a channel with cheaper trials but lower conversion can be worse.
To reach a new-MRR goal, divide it by the price to get the customers needed, then divide by the conversion rate to get the trials needed. Or divide the customers needed by your current trials to get the conversion rate you would need instead.
A worked example
400 trials a month at 15% conversion give 60 new customers. At $49 a month that is $2,940 of new MRR, or $35,280 of new ARR each month. At $20 per trial, each paying customer cost $133.33, and every trial is worth $7.35 a month. To add $5,000 of MRR a month you need about 102 customers: 680 trials at 15%, or a 25.5% conversion rate on your current 400 trials.
Questions people ask
What is a good trial to paid conversion rate?
It depends heavily on the trial type. Trials that ask for a card up front usually convert at a much higher rate than trials that don't, because fewer casual users sign up. Compare your own rate over time and between channels rather than against a single benchmark.
How do I calculate trial conversion rate?
Customers who paid after a trial ÷ trials that ended in the same period. Use trials that have finished, not trials still running, or the rate will look lower than it is.
Why is cost per paying customer higher than cost per trial?
You pay to acquire every trial, but only some convert. Dividing cost per trial by the conversion rate spreads the cost of the trials that didn't convert across the ones that did.
Is it better to get more trials or improve conversion?
Compare what each costs. Raising conversion from 15% to 18% adds as many customers as 20% more trials, and it also lowers acquisition cost per customer, so onboarding improvements are often the cheaper lever.
How does this connect to LTV and CAC?
The acquisition cost per paying customer here is your CAC for this channel. Put it into the LTV to CAC Ratio Calculator with your price, margin and churn to see whether the channel pays back.