I find this hilarious when watching DIY videos on YouTube. All the makers are talking about "5/16 of an inch" and I'm trying to convert this to a metric value

I find this hilarious when watching DIY videos on YouTube. All the makers are talking about "5/16 of an inch" and I'm trying to convert this to a metric value and it doesn't make any sense at all, because "complex" fractions like this are not used in every day life.