Honey for mead - but how much

To put honey aside for a mead I need to figure out how much I need. I have been looking for another yeast that gives a bit less alcohol and I found a mead yeast capable of 15% given the best conditions   (White Labs WLP-720)

 

Last year my yeast maxed out at 16% and changed the gravity by about 115. Ken Schramm specifies a gravity change og about 100 for a 14% yeast, i.e 1% per 7(+) gravity change.

7.2 kg to 20L gave a OG of 120. If i want the mead to be a bit sweet I want FG to be around 20, so with a 15% yeast I need an OG of 20+100+7 = 127. Assuming that the water content was like last year I need to start with 7.2kg / 120 * 127 = 7.6kg

So 7.6 kg was collected in a 10L container. When used, i just need to wash the entire content into the pot. The container can easily be washed on the outside before I make the mead so i can just pour water back and forth to ensure that the entire mass of honey is dissolved

This will be the base mead. I will likely end up making melomels so now is the time to select berries...