Howrah Railway Station to Airport : Check for Prepaid Taxi Counter - for one entire cab Rs 302 only. There are 4 to 5 counters outside station and easy to find cab.
I see basic fare for 2km is mere Rs 55.
Howrah to Sealdah Rs 110.
Do not fall victim of Ola or Uber or roadside agent demanding exorbitant number 600-700 Bucks.