According to this random study I googled up, it is in the neighborhood of 2%: ht...

		mikeash on July 3, 2018 \| parent \| context \| favorite \| on: We're All Subsidizing People Who Use American Expr... According to this random study I googled up, it is in the neighborhood of 2%: http://fletcher.tufts.edu/CostofCash/~/media/Fletcher/Micros... (PDF, per transaction costs of cash are discussed on page 25.)