Êxodo 30:13

13 Each one who crosses over to those already counted is to give a half shekel, That is, about 1/5 ounce or about 5.8 grams; also in verse 15 according to the sanctuary shekel, which weighs twenty gerahs. This half shekel is an offering to the Lord.

13 This they shall give, every one that passeth over unto them that are numbered, half a shekel after the shekel of the sanctuary; (the shekel is twenty gerahs;) half a shekel for an offering to Jehovah.