Both in the US and EU, one packet of active dry yeast is 1/4 oz (7g). The one I use says on the package that 7g active dry yeast is equivalent to 25g fresh yeast, which is enough for 500g flour. In the US, one block of fresh yeast (like this one) is 2 oz (57g), but in the EU, one block of fresh yeast is 50g. This difference will not affect the result.