Often overlooked but one of the most crucial factors to optimizing game performance and avoiding arm injuries is string tension. Understanding how it can impact a game can help upgrade your skills and boost your winning potential. Let’s uncover Roger Federer’s racquet string tension and learn from the world’s best.
Irrespective of tensions, Federer’s racquets are often strung with 1.25mm Luxilon ALU Rough in the cross strings and with 1.30mm Wilson (Babolat) Natural Gut in the mains.
During the Chicago Laver Cup in 2018, he strung his mains at 27kgs (59.5lbs) and his crosses at 25.5kgs (56.2lbs).
Players tend to change their string tension as they see fit, depending on the playing conditions. They might take the tension up or down a couple of pounds.
Any changes made to the string tension will be influenced by surface, temperature, altitude, and the opponent. 
How About the Mains & Crosses?
Federer prefers his tennis string to be relatively consistent and stable. His mains are strung tighter to create a more consistent feel across the string bed. He always strings his main strings one and a half kilogram greater than his cross strings. This setup is believed to create a more powerful sweet spot in the middle of the racquet.
He often uses seven or eight racquets strung at different tensions in a five-set match. He tends to go tighter as the game progresses.
Stringing the crosses at a lower tension increases the sweet spot of the racquet. If you use a softer string like a natural gut in a hybrid string setup with a stiffer string, the former needs to be strung at a higher tension. Learn how to string a tennis racquet here.
Such configuration helps to approximate a similar level of stiffness compared to elastic strings in the crosses and therefore creates a more consistent feel across the string bed.
Federer's String Tensions Over The Years
Federer has switched to a new 97 square inch racquet from the long-term 90 square inch racquet.
He strung at around 22 to 23 kilograms with the smaller head size, while with the larger head size, he strung up at 26 to 27 kilograms.
The tension change was due to the increase in the size of the racquet head. The string’s stiffness when tensioned is directly proportional to the length of the string.
He had to amp up the tension on the bigger racquet to maintain a consistent feel and power.
Federer & Priority 1
Priority 1 is quite reputable and consistent in its services. Hence, Federer is a loyal client. He often obtains services from Ron Yu, who brings stringing machines that are accurately calibrated for every tournament they join. This ensures that Federer gets the same feel on his racquet no matter where and who his opponent is.
Amazingly, Yu tries to be consistent with the time duration when the racquets come off the machine to when Federer is scheduled to play throughout the tournament. He does this because the stringbed changes tension depending on how long the racquet stays idle around before the play.
The string tension that professionals use ranges between 40-65 lbs. Generally, racquets should be strung as low as possible while still exerting power and maintaining control of the ball. At the start of the play, it’s suggested to string at 23kgs to 27kgs to avoid injuries.
Tennis strings begin to lose tension as soon as they come out of the stringing machine. The amount of tension loss depends on the type of string. Strings can lose around 10% of their tension after 24 hours of stringing, and this progresses as you play with the racquet.
Revealed: Federer's Racquet String Tension
While learning the techniques of a pro doesn’t necessarily make you an instant pro yourself, it’s enlightening to know that it’s not all about prowess or luck that wins a game but also choosing the proper equipment configurations.
Racquet string tension is a matter of personal preference, but it helps players gain more power and control and minimizes the risk of injuries. Roger Federer is a highly-acclaimed professional tennis player who has stereotypical tension string preferences.
He prefers his strings to be consistent and uses a particular tension that draws out his best shots and techniques in the game.