Perhaps, but if you have a water quality report from your city (check online; they often post them there) then you can probably find both Calcium Hardness and Total Hardness listed separately and usually if only one is listed it's Total Hardness. I have found from my own testing that the numbers in the water quality report match what I measure at the tap.

With something as important as properly sizing the water softener, I would either use the water quality report data or get a real Total Hardness test. The factor of 1.4 is a nice rough estimate, but it could be totally off depending on your specific water situation since it's dependent on the kind of rocks the water has filtered through.

Richard