How to get object size in memory? [duplicate]

Question

this may not be accurate but its close enough for me

long size = 0;
object o = new object();
using (Stream s = new MemoryStream()) {
    BinaryFormatter formatter = new BinaryFormatter();
    formatter.Serialize(s, o);
    size = s.Length;
}

I don't think you can get it directly, but there are a few ways to find it indirectly.

One way is to use the GC.GetTotalMemory method to measure the amount of memory used before and after creating your object. This won't be perfect, but as long as you control the rest of the application you may get the information you are interested in.

Apart from that you can use a profiler to get the information or you could use the profiling api to get the information in code. But that won't be easy to use I think.

See Find out how much memory is being used by an object in C#? for a similar question.

Unmanaged object:

• Marshal.SizeOf(object yourObj);

Value Types:

• sizeof(object val)

Managed object:

• Looks like there is no direct way to get for managed objects, Ref: https://docs.microsoft.com/en-us/archive/blogs/cbrumme/size-of-a-managed-object

OK, this question has been answered and answer accepted but someone asked me to put my answer so there you go.

First of all, it is not possible to say for sure. It is an internal implementation detail and not documented. However, based on the objects included in the other object. Now, how do we calculate the memory requirement for our cached objects?

I had previously touched this subject in this article:

Now, how do we calculate the memory requirement for our cached objects? Well, as most of you would know, Int32 and float are four bytes, double and DateTime 8 bytes, char is actually two bytes (not one byte), and so on. String is a bit more complex, 2*(n+1), where n is the length of the string. For objects, it will depend on their members: just sum up the memory requirement of all its members, remembering all object references are simply 4 byte pointers on a 32 bit box. Now, this is actually not quite true, we have not taken care of the overhead of each object in the heap. I am not sure if you need to be concerned about this, but I suppose, if you will be using lots of small objects, you would have to take the overhead into consideration. Each heap object costs as much as its primitive types, plus four bytes for object references (on a 32 bit machine, although BizTalk runs 32 bit on 64 bit machines as well), plus 4 bytes for the type object pointer, and I think 4 bytes for the sync block index. Why is this additional overhead important? Well, let’s imagine we have a class with two Int32 members; in this case, the memory requirement is 16 bytes and not 8.

The following code fragment should return the size in bytes of any object passed to it, so long as it can be serialized. I got this from a colleague at Quixant to resolve a problem of writing to SRAM on a gaming platform. Hope it helps out. Credit and thanks to Carlo Vittuci.

/// <summary>
/// Calculates the lenght in bytes of an object 
/// and returns the size 
/// </summary>
/// <param name="TestObject"></param>
/// <returns></returns>
private int GetObjectSize(object TestObject)
{
    BinaryFormatter bf = new BinaryFormatter();
    MemoryStream ms = new MemoryStream();
    byte[] Array;
    bf.Serialize(ms, TestObject);
    Array = ms.ToArray();
    return Array.Length;
}

In debug mode

load SOS

and execute dumpheap command.