Rock and metal fans have plenty of great songs to choose from for their next road trip playlist.

But just how many tunes should be on it? Is there some magic number of tracks that make the perfect length for a rock road trip playlist?

Car insurance experts at Uswitch.com, a U.K. price comparison website, claim to have found that number for specific trips. And not just for rock, but for many different music genres.

For those about to rock, the results posit that a rock song's average runtime — and therefore the usual length of rock playlists — can make the perfect mix for some iconic road trips.

The study looked at the 10 most popular road trips in the U.S. and abroad, including notable stateside destinations such as the historic Route 66 (No. 1) and California's Big Sur Coast Highway (No. 2). Also on the list were Australia's Great Ocean Road (No. 3), Ireland's Wild Atlantic Highway (No. 4) and Snowdonia National Park in Wales (No. 5).

Considering trips of great distance, rock music fared as one of the best for lengthy drives. Perhaps unsurprisingly, it came in second only to instrumental music, which has an average playlist track count of 200 and average playlist times good for a 10-hour trip.

"Rock music is the perfect choice for journeys up to 6.6 hours long (six hours and 36 minutes with an average of 63 songs), while classical music will be best suited for journeys up to 5.7 hours (five hours and 42 minutes with an average of 74 songs)," the report explains. "If you are after a slightly alternative genre of music, for journeys up to 5.5 hours (five hours and 30 minutes and 91 songs), give a gaming playlist a go."

The study further breaks down which tracks are best suited for each of the trips. For traversing all of Route 66, you'll need a playlist with 474 rock songs. For Big Sur, only 32. Cruising the Pacific Coast Highway requires a rock playlist of 415 songs, while taking the Blue Ridge Parkway entails 156. The respective numbers for metal are slightly different.

Uswitch says it "pursued this research to evaluate the popularity of road trips by the number of music tracks required to complete them. Road trips were sourced from a seed list based on the total number of Instagram hashtags, and they were ranked accordingly."

The trip durations were taken from Google Maps with educated guesses for start and end points. Playlist data was extracted from Spotify, gathering the 10 most popular playlists in each genre, 100 total of which were selected. Calculations were then made to find the average playlist duration in each genre and its respective average number of songs.

Read the full study and see graphic representations of the results here.

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