Very simple guide, about men's shirt size, decoded.
A shirt is always measured by a collar length.
A collar is the pivot point for men's shirt.
If you see size 40, this means the length of the collar is 40 cm.
Similarly, size 42 means, the length of the collar is 42 cm.
Collar length is universal. Other measurements like chest, waist, sleeves, the shoulder can be different for different countries or manufactures.
A size 40 shirt from one brand may have 42 inches chest length, and for another brand, it may have 44 inches chest length.
A size 40 shirt in Slim fit may have 42 inches chest length, and for Regular fit, it may have 46 inches chest length within the same brand.
In the physical store, it's easy to put on trial for the right fit shirt.
However, for online purchase, it is very important to go through the shirt size chart.
Now you know, shirt size, let's move on to find your match.
One must know his body measurement.
Neck Length: Put the index finger between the tape and neck while measuring the neck. You will get your collar size.
If your neck length is 39.2 then round it off, and choose the shirt with collar size 40.
Chest: It's easy, just take your chest measurement (widest part of your chest).
Just add 4-5 inches for space and total is your Shirt chest length. This is for the slim fit.
If you want loose fitting, add 5-8 inches to the chest length.
If your chest measurement is 38 inches, then add 4-5, the total 42-43 is your final shirt length.
Your final Shirt size is 40 with collar 40 cm, Chest 42 inches, Waist, sleeves, shoulder and shirt length is automatically graded according to the collar and chest.
So basically you have to look for the only collar, chest, and fitting (slim or regular), when you select a shirt.