I'm just trying to find out the standard dev between 2 numbers for a work project. A number in a population (17.35%) and the mean of said population (14.65%). An online calc yields an STDEV of 1.35% whilst Excel (using the sample stdev formula) yields 1.90%.

I'm not sure if the online calc takes into consideration that it's a sample because when I divided by N-1 (or 1.... is this even right?) I got 1.90%.

Am I even doing this right?

Thank you all in advance for the help. Any and all is appreciated.