One Knox powdered gelatin envelope (US)
= 1/4 oz, about 7 grams.

1 (US) envelope:
= 7 g,
= 7 (1-gram) sheets,
= 4 (1.66-gram) sheets,
= 3 or 3 1/2 (2-gram) sheets.

1 (Europe) envelope:
= 11 g
= 11 (1-gram) sheets,
= 6.5 or 7 (1.66-gram) sheets
= 5 (2-gram) sheets

source: rec.food.cooking