This app is using to converting amounts from Gram to Kilogram as well as converting amounts from Kilogram to Gram.

First of all, let us talk about gram type and Kilogram type:

Gram (g):

The gram (alternative spelling: gramme; SI unit symbol: g) (Latin gramma, from Greek γράμμα, grámma) is a metric system unit of mass.
Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm3], and at the temperature of melting ice" (later at 4 °C, the temperature of maximum density of water).
However, in a reversal of reference and defined units, a gram is now defined as one thousandth of the SI base unit, the kilogram, or 1×10−3 kg, which itself is now defined by the International Bureau of Weights and Measures, not in terms of grams, but by "the amount of electricity needed to counteract its force".


Kilogram (kg):

The SI unit of mass, equivalent to the international standard kept at Sèvres near Paris (approximately 2.205 lb).
The kilogram or kilogramme is the base unit of mass in the International System of Units. Until 20 May 2019, it remains defined by a platinum alloy cylinder, the International Prototype Kilogram, manufactured in 1889, and carefully stored in Saint-Cloud, a suburb of Paris.


By the way, As far as I told, this app is useful for converting amounts from Gram to Kilogram and vise verse.
So let's start using this android application.