I've shared my Jam Recipe a while ago @cyclamen.
Here it is the link: https://steemit.com/food/@awesome-seven/jam-homemade
More likely it should be 1kg of sugar per 2 kg of berries.
I don't follow these proportions.
I measure "with my eyes and my taste"
If the berries are sweet I use less sugar and vice versa.
I don't like when the jam is too sweet yet I use enough sugar to keep it safely in the jar throughout the winter.
Sorry, for the delay in getting back to you :)