Compare every option over the same period, including maintenance, down payment, installments, final ownership and residual value. A small monthly payment can hide a large upfront outlay.
An example with numbers
Buying costs $12,000 and you expect to get $3,000 back when selling in three years. Renting costs $300 a month for 36 months. The nominal costs would be $9,000 and $10,800 if maintenance were identical. The payment schedules are different.
Try it with your numbers
Note the cash flows by date and try a lower residual value. Then compare present values if your cost of financing matters.
This calculator is on its way. In the meantime, you can do the calculation on paper or in a spreadsheet.
Example figures for learning purposes. They are not a recommendation and do not replace professional advice.