soil/compost ratio

In my opinion it depends on a few things. What are you going to grow in the beds, Flowers??, Vegetables??? Also what sort of soil is it you want to use, Sandy?, Loamy?, Clay??. I have sandy soil but even so I add grit when growing flowers to help the drainage and the soil compacting. But I wouldn't use grit if I was growing veg like Carrots or Leeks.

 

We have a lot of veg experts on GC, some of who use raised beds.........so, hopefully, some on them will give you advice on that......but 50/50 sounds reasonable to me, but then I'm a flower man!!