Exodus 30:13

13Everyone who crosses over to those counted must pay a half shekel,30:13 A half shekel is approximately 0.2 ounces or 5.7 grams; also in verse 15. according to the sanctuary shekel, which weighs twenty gerahs.30:13 20 gerahs is equivalent to one shekel (approximately 0.4 ounces or 11.4 grams). This half shekel is an offering to the Lord.