https://www.amazon.com/Park-Tool-Por.../dp/B079YW26GQ

For $35 for the park tool it is hard to argue with having the proper tool. There may be other ones available. As [MENTION=381793]gugie[/MENTION] mentioned you can do a lot without buying the tool but they make doing things easier. I see there are also some copycat tension meters on Amazon these days for dirt cheap. Not sure about accuracy but makes things easier.

https://www.amazon.com/gp/aw/d/B088Q...TF8&psc=1&th=1