What's the equation for converting mass into weight?

Answer 1

There is no equation to convert mass into weight, because it all depends on the density of the material. Even something as simple as a liter of water won't always weigh the same each time, because the temperature will change its density. Hot water is less dense than cold water, therefore the same volume of hot and cold waters don't weigh the same. Another example. Take a gallon of flour and weigh it. Now fill that same gallon container with sand and weigh it. It will not weigh the same because sand is denser than flour.
The bottom line is, you can't convert mass into weight because there are too many variables for one equation to solve all problems.

Answer 2

Answer is here: http://mathforum.org/library/drmath/view/56250.html