I have an Amazon Echo in my shop. I can't tell you how many times a day I say "Alexa convert xyz inches to mm" Whatever government employee is assigned to monitoring my search activity must think I have the mind of a goldfish because I can't remember even the most basic metric conversions to save my life. Pretty ironic considering I spent my first 23 years in Canada under under metric and the last 15 down here...you'd think I'd be pretty well versed.
Anyway point of all that was I find Siri or other voice activated device (like my echo) much faster with conversions than stopping to look at a chart. I like that I don't have to take my hands off of or stop what I'm doing.