A quick way to measure body fat/muscle mass for each body compartment is by using those commercial health scale.. Just purposely go to a commercial gym (should have one) and say u wanna take up their trial. they will intro you to the gym and let you assess ur body composition and print out the report for u free.. after a month or so just try at another gym for benchmarking again.

@Armesh I once gained 9kg when beginner stage in 3 months, out of it ~6kg were muscles and was taking mass gainer. And i have fortnightly report to track the progress. its possible at early stages