How to check Sizeof(MyClass) in unity4.5.and mono 4.0.1

Hi ,
I was trying to find the sizeof(myclass) in unity,but i am unable to use Marshal.sizeof(myClass) in mono.
so pls let me know is there a way to determine the sizof(myClass) in unity3d4.5

Thanks in advance.

Sizeof works in Unity as well:

But I am not sure whether this is what you want to achieve. What is your goal?

You cant get size of object if you dont use unsafe coding (marshal)
You can use a tool like:

CLR Profiler
VSTS Profiler
.NET Memory Profiler

@DiRe
Thanks for the reply , I will look into it.
Sorry for the late reply