Migs use volts. Try https://www.millerwelds.com/resources/weld-setting-calculators/mig-solid-core-welding-calculator for a place to start. Also available as an app for your phone. I like this guy's youtube videos coz he knows what he is talking about, isn't a ******, and gets straight on it. Oh, and he doesn't begin his videos by saying "Hey, wassup guys". Oops forgot the link, silly me. Here you go.