With holiday travel approaching using airline miles and points is a smart way to avoid a possible hefty price tag. However, certain award currencies provide better value than others during peak travel times.

NerdWallet, a personal finance website, analyzed flight prices for travel between December 22 and December 29 of this year, comparing the rates when paying with cash or miles. Out of all of the major airline currencies, using Frontier Airlines miles can offer the best deal as they’re worth 1.8 cents apiece, the company shared with Travel + Leisure.

American Airlines miles ranked second, worth roughly 1.6 cents per mile, while JetBlue points and Southwest Airlines points tied at 1.4 cents apiece. On the lower end, the study found that Spirit Airlines points were valued at 1 cent each, followed by Hawaiian Airlines miles at 1.1 cents and Delta Air Lines and United Airlines miles at both 1.2 cents. 

NerdWallet updates its rewards valuations annually, accounting for peak and non-peak travel periods, in an ongoing guide. 

“Unlike many point and mile valuations, ours are drawn from real-world data,” the company shared. “They are not hypothetical or maximized values based on idealized conditions but actual estimates of how many cents per point or mile you can expect to get when making award bookings.

How exactly is the value of an airline mile determined? Award flights usually charge taxes and fees, typically $5.60 for one-way tickets within the U.S. To calculate the value of a mile, the cash price of the flight is subtracted by those taxes, and the remaining amount is divided by the number of miles needed for the same ticket. Multiplying this figure by 100 will result in the value of each airline mile in cents.

Calculating these values can help you assess if you’re getting the most out of your hard-earned airline miles, but there are also free tools to simplify the process. Points Path, a free browser extension, automatically compares real-time cash prices to airline miles on Google Flights, showing whether redeeming rewards is truly a good deal.