1mg below the level of electronic precision balance
0.1mg called electronic analytical balance
0.01mg called quasi-microbalance
1ug called microbalance
0.1ug and above known as ultra-micro electronic balance

100mg = 0.1g                                     = one tenth
10 mg = 0.01 g                                   = 1%
1 mg = 0.001 g                                   = one thousandth
0.1mg = 0.0001g                                 = one ten thousandth
0.01 mg = 0.00001 g                           = one hundred thousandths
1 μg = 0.001 mg = 0.000001 g             = parts per million
0.1 μg = 0.0001 mg = 0.0000001 g       = one millionth