Manufacturers name gauges differently, but 45–105 is usually considered a standard or medium-light set. Common directions from there:
- Lighter (like .040–.095 or .045–.100): more flexible and responsive. Many slap players like them.
- Heavier (like .050–.110 or more): a firmer feel and more low-end response. Many metal players use them, especially in lower tunings.
Heavier isn't automatically better. At the same pitch and scale length, heavier strings feel stiffer, while lighter strings are easier to play. Heavier strings aren't necessarily louder either, since output depends on pickups, setup, technique and amplification.
Professionals use a wide range of gauges. Many start at 45–105 on a 4-string or 45–125 on a 5-string and adjust from there. If you're happy with how your bass plays, staying with your current gauge keeps the setup the same.