The present study attempts to quantitatively estimate total potassium content in soil samples collected from different areas of Indian Sundarbans by gamma-spectrometry, exploiting the radiogenic properties of potassium and by wavelength dispersive X-ray fluorescence technique. The elemental K concentration varied in between 2.08 ± 0.05 and 3.46 ± 0.06% in the soil samples. Besides estimation of total potassium, the activity of 40K was also estimated in the same soil samples and found to be in the range of 532 ± 8.9 to 1043 ± 13.2 Bq kg−1. © 2019, Akadémiai Kiadó, Budapest, Hungary.