Tennis Warehouse maintains a string testing database. It provides invaluable information about strings. You can access the database here: https://twu.tennis-warehouse.com/learning_center/index.php

There are two ways to use the database:

1. Comparing two strings
2. Filtering the database

Comparing two strings

You can compare two strings – typically this would be your current string (or another string that you know well) with another new string: https://twu.tennis-warehouse.com/learning_center/comparestrings.php

In the above example, I have chosen Babolat RPM Blast (1.25 mm gauge) and HEAD Lynx Tour 17 (same gauge):

• Stiffness: My suggestion would be to stay below 220 ib/in. If you like a stiffer string, then you can safely drop the tension.
• Tension loss: This is an indication for how long the string retains its playability. Most more modern strings will retain its tension longer than older strings and mid 20 is good. A stiff string with a higher tension loss percentage can quickly become very stiff and hurt your arm, so it will need to be changed more frequently.
• Spin potential: The higher number can equal more spin, but it is dependent on your technique. RPM Blast is known as a string with high spin potential, but the spin is generated by string “snapback” rather than ball grip and snapback requires fast racquet head speed (aka good technique).

So if you use the RPM Blast and you’d like more spin and comfort, then RPM Blast Rough is a good option (assuming you want to stay with the brand):

Filtering the database

If you are not sure what (alternative) string to choose, then filtering the database is one way to find a string: https://twu.tennis-warehouse.com/learning_center/reporter2.php

If you are looking for a string with better comfort, then you are looking for a string a lower stiffness and lower tension loss percent than your current string. You’d sort the result by brand to make it easier to pick a string that you know you can buy.

The above filter will produce the below table. As you can see, there are some exotic strings… This is only a small snippet of the complete set and you can (although it is fiddly) copy the data into a spreadsheet. But you can see most of Babolat’s strings and compare in one go, and on the live site, you can see all vendors.

One Caution

Take the data as a rough guide only, and if the string feels and plays different to the numbers, then go with your feeling.

For example, I use HEAD’s Lynx Tour 1.25mm (mains) and Lynx Touch 1.25mm (cross). I added the Lynx Touch to increase the comfort and power, and it is a softer string by feeling. The database suggests, that Lynx Touch 1.30mm is more like the Lynx Tour, but I guess 0.05mm can make a huge difference, maybe?

Bottomline is that my racquet strung with just the Lynx Tour feels significantly stiffer and less powerful than with a mix of the two.