The content is accurate at the time of publication and is subject to change.

Free Spirit, the frequent flyer program of Spirit Airlines, allows to earn miles every time you fly. You can earn Spirit miles using Spirit Airlines Mastercard which comes with a 15,000-mile sign-up bonus and gives 2 miles per dollar spent on every purchase. Spirit World Mastercard cardholders earn 100% of the miles flown when using the card to purchase flights.

Another way to earn more Spirit miles is to participate in partner programs. For example, you can earn additional FREE SPIRIT miles with car rentals as Hertz, Avis, with hotel chains like Choice Hotels and with other partners.

You can buy Free Spirit Miles for your award booking starting from $25 for 1,000 miles if you are short of miles. It is important to mention that this program is very restrictive as your miles expire after only three months of inactivity even if you are a cardholder.

While you might expect a co-branded Spirit credit card to be the best way to earn Free Spirit rewards, you would be mistaken. Travel rewards cards that allow you to redeem points toward any travel purchases, not just those made with one airline, and have generous rewards, seem to offer more.