On this page you can find out the number of atoms of each different element in your body, as well as find out the actual mass of gold. Enter your mass in kilograms into the first box. If you only know your mass in stones, enter your mass in the 2nd box and your mass in kilograms will be calculated in the third box. You will need to manually enter this calculated mass back into the first box. Scroll down to find out the actual mass of gold, poisonous arsenic and uranium in your body. (Spoiler: you're not going to get rich off the gold content!) At the bottom, you can find a set of instructions to calculate the mass of any of the other elements.
How to calculate the actual mass of any other element in your body
Copy the number of atoms of the desired element. I’ll use sodium as an example. An average person of 70kg contains:
2.50 x 1024 atoms of sodium
Divide by Avogadro’s number (6.02 x 1023), which will give you the number of moles of the element
= 2.50 x 1024 / 6.02 x 1023
= 4.15 moles
Finally, multiply by the relative mass of the element (Mr sodium = 23)
= 4.15 x 23
= 95.51g sodium in an average male of 70kg
Which is quite a lot! For comparison, a small chocolate bar (costing about 70 pence) has a mass of roughly 100g, depending on the brand. On reflection, this is not too surprising as sodium is absolutely vital for the functioning of many cells, especially the neurons that compose our nervous system, comprising our brain and all our nerves.