If you have the TPC velocity vs. angle curve, and you don't have surfactant, then fit the data with Blake-Hines model (for a hydrophobic surface) or Voinov model (for a hydrophilic). If they both don't go or you have surfactant, then use your imagination and extrapolate velocity to zero. If there is evaporation, you can make a mistake of several degrees (you will find a smaller angle).

If you have only the hysteretic advancing and receding angles, the best thing you can do is to use the average.

Thanks a lot Radomir Slavchov. I have Contact angle with time data. And i want to calculate the angle. The contact angle is high initially and later is becomes constant with time.

...spreading droplet? From theta vs. t you obtain the advancing angle only. Try to make the droplet move, e.g., by inclining the substrate, to get both adv. and rec. angles.

You can take a look at the publications of https://www.researchgate.net/profile/Carlos_Fuentes9

He's a researcher in my group with great expertise on dynamic contact angle measurements.