Exodus 30:13

13Each one who is numbered in the census shall give this: half a shekel
A  shekel was about 2/5 ounce or 11 grams
according to the b  shekel of the sanctuary (the c  shekel is twenty gerahs),
A  gerah was about 1/50 ounce or 0.6 gram
e  half a shekel as an offering to the  Lord.
Copyright information for ESV