Two setups.
One clearer choice.

These are trial settings, not manufacturer-approved prescriptions. The demo starts an open-pattern polyester bed near 22 kg and a dense 18×20 near 20 kg, then adjusts for construction, qualitative firmness and player preference. For 18×20 you can explore 18–22 kg; other patterns use 19–24 kg. Multifilament and gut generally start higher than polyester.

Check the frame's tension guidance and stringing instructions with your stringer. Low settings can sit outside the manufacturer's reference range. Reassess after a short hitting session in 0.5–1 kg steps. Do not use the estimator as medical advice or as a guarantee of arm comfort.

The comparison is rule-based, not a physics simulation. It cannot predict measured spin, ball speed or exact string life. If play causes pain, stop and seek qualified advice rather than relying on a lower tension.

Recommendation references: Tennis Warehouse · tension · TW University · friction & spin · Solinco · Confidential Soft