There is, but I’m gonna let you read up to figure out the details.
The Alarm Clock thread has some good examples of using input_sliders. Sliders have a step attribute, so you should be able to have 0-80 in the UI, then do the math in your automation.
You’re going to want to look at using templates, replacing “data” in the sample I gave you above with “data_template”. Then do the math there to convert 80ths to percents.
The template dev tool is a good place to work those rules out before saving as an automation.