Why there is difference in the measurement With the Measure tool i have draw the line to measure the model. It shows 6.03. Where as in the N panel under dimensions in the z axis it shows 5.18. Why there is difference in the measurement

I tried to scale the complete model but some parts disappear.

Any solution to get perfect measurement for the model.
Measurments differs because Dimension displays size of Active object only.
With Measurment Tool you measure all objects.