is this formula correct to measure the accuracy of kwh meter incomparison with stopwatch?

Question

3600 x1000/volts x amps(total) x p.f x meter constant

Answer 1

In comparison to a stopwatch? Are you timing your meter or something?

You have the basics down - V*A*(power factor)*3600 seconds*meter

There are fluctuations in the overall system that will make the system vary greatly. Also in home construction the efficiency of the electrical system will vary as the electricity has a voltage drop depending on the distance of the run to the device.