NORTON 15 : How to calculate the necessary size of the destination drive ?

On my current PC the situation is :

   - One 119 GB SSD drive with 46 GB of data

   - One 20 GB partition of an HDD with 3 GB of data

   - One 130 GB partition of an HDD with 80 GB of data

I use the whole disk backup and it ends up with a recovery space on external disk of : 286 GB

Is it normal ?

 

What I plan on another PC is to backup :

   - One 128 GB SSD

   - One 1TB HDD

What size should I plan for the external backup drive, supposing the internal drives are full ?