That is pricing for 1st Generation, which is a whole different product that does not support Postgres. The pricing for Postgres is here: https://cloud.google.com/sql/docs/postgres/pricing#pg-pricin...

    (1*0.0413+2*0.0070)*730 + 5*0.17 = $41.22/month
      1 vCPU   2GB RAM        5GB SSD