The following Snippet will iterate over Tables and print out their total of elements simply navigate to your rails project and run rails c:

ActiveRecord::Base.connection.tables.each do |table|
  next if table.match(/\Aschema_migrations\Z/)
  klass = table.singularize.camelize.constantize      
  puts "#{klass.name} has #{klass.count} records"
end

No more guesstimations ;-)

credits: Thomas E