The Gram is a metric system unit of mass. a gram is now defined as one one-thousandth of the SI base unit, the kilogram, or 1×10−3 kg.
Kilogram (kg) symbol kg, is the base unit of mass in SI. one kilogram is equal to 1000 gram
The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement.
The tonne is commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms