Grab an app like dminder. There's a lot of variables, some you can control and some you can't. In a bathing suit in Mexico in summer, a fair skinned person wil

Grab an app like dminder. There's a lot of variables, some you can control and some you can't. In a bathing suit in Mexico in summer, a fair skinned person will produce their entire daily allotment in just a few minutes. But that same person with pants and short sleeves might need an hour or more in Michigan in spring.