How can I change one color to given other color?

I have an image with a simple blue and I want to change it to a specific color, R 0, G, 128, and B 128. The problem is that after I've selected the color and created a new adjustment layer for hue/saturation, my only choice is hue/saturation and the way Photoshop assigns values to them appears arbitrary. It doesn't reflect how any web conversion tool I can find does it. For example, the tool at https://www.rapidtables.com/convert/color/rgb-to-hsl.html converts the final color as H 180, S 100, and L 25.1. This doesn't map at all to Photoshop's value system, which appears to be H, -180 to 180, and the other two from -100 to 100.