How to Know the Graphics Memory Size and Usage In OpenGL



ATI Radeon

You’re an OpenGL developer and you need a simple way to know graphics memory information such as the memory size or memory usage? If so, this is the right place!

Few years ago, this kind of information wasn’t available to OpenGL developers but today, the two majors in OpenGL (I mean NVIDIA and AMD/ATI) have added some useful extensions to fetch graphics card memory size and other related data.

OpenGL Memory Size with NVIDIA

NVIDIA has recently published the specs of a new extension called GL_NVX_gpu_memory_info.

Thanks to GL_NVX_gpu_memory_info you can retrieve the size of the total available GPU memory and the size of the current available GPU memory.

Here is a code snippet that shows how to use it. GL_NVX_gpu_memory_info returns sizes in KB.


GLint total_mem_kb = 0:

GLint cur_avail_mem_kb = 0:

This extension is used in GPU Shark to get the memory usage for NVIDIA graphics cards as you can see in the following picture:

Memory usage - OpenGL - GeForce  GTX 260

According to Geeks3D OpenGL extensions DB, GL_NVX_gpu_memory_info is available in NVIDIA display drivers since R196.xx (see R196.21).

OpenGL Memory Size with AMD/ATI

AMD has released two extensions to deal with the size of video memory:

WGL_AMD_gpu_association is an extension developed for parallel rendering: you can create a different OpenGL context on each available GPU. This extension comes with hardware query functionalities. With WGL_AMD_gpu_association you can get the amount of graphics memory available for the GPU.

Here is how to use it to get the size of GPU memory in MB:

UINT n = wglGetGPUIDsAMD(0, 0);
UINT *ids = new UINT[n];
size_t total_mem_mb = 0;
wglGetGPUIDsAMD(n, ids);

I tested this extension in this pico tool called Radeon-Z 😉

Memory usage - OpenGL - Radeon HD 5870

GL_ATI_meminfo is used when you need more detailed information about the available memory for VBO (vertex buffer object) or for your textures.

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18 thoughts on “How to Know the Graphics Memory Size and Usage In OpenGL”

  1. Pingback: [GPU Tool] RADEON-Z 0.1.0: OpenGL Information Utility for ATI Radeon Cards - 3D Tech News, Pixel Hacking, Data Visualization and 3D Programming -

  2. JeGX Post Author


    I must say that right now I’m a bit too lazy… I’ll try to update the post with an ATI_meminfo code snippet.

  3. filip007

    It’s about time to add some mem info to any bench how hard is that…

  4. fjfjfgjfgj

    It would be handy to know the memory a specific application is using. Hopefully this becomes part of OpenGL.
    Standardizing this kind of diagnostical help is a great oppertunity to make life easier for optimization. I’m loving it.

  5. fjfjfgjfgj

    Also for the memory sizes.

    Is that in MB as in 1000000B or 1024^2B?
    Same for kB: 1000 or 1024?

    I’m hoping it’s 1000 and 1000000 we have KiB and MiB for the powers of two.

  6. jammer

    Use of GL_ATI_meminfo is very simple 🙂

    int free_mem;
    //returns in kB, so if you want MB,divide by 1024
    //now subtract this free memory from total memory and get used memory 🙂
    used_mem = total_mem – free_mem;

    I’ve noticed that it doesn’t matter whether you give to this function GL_TEXTURE_FREE_MEMORY_ATI or GL_VBO_FREE_MEMORY_ATI, it returns the same numbers

  7. Dan

    Would it be possible to add peak memory usage while program running in tray and playing opengl game? Like in MemStatus tool -_-

  8. fjfjfgjfgj

    It is working in powers of two with the WRONG PREFIX!!!

    Thanks jammer, this was indeed necessary to know.
    They should move to MiB and KiB notations.

    And about memory for an application.
    Seperate for memory that an application has resources only used by itself and resources shared for other things.

  9. Lightness1024

    This information was prefiously already available with the tool “memstatus”. I tested it on various cards (even gtx with 197 drivers) and it worked only on quadro up to now, though.

  10. fjfjfgjfgj

    About: Seperate for memory that an application has resources only used by itself and resources shared for other things. It would be very useful to have that distinction.

  11. Mars_999

    I am having a crash when I call wglGetGPUInfoAMD()… I take out that call and I have no issues?

    AFAIK I don’t need a GL3+ RC I am using GL2 RC.


    GLuint gpuIDs[16] = {0};
    GLuint maxGpus = wglGetGPUIDsAMD(16, gpuIDs);
    GLint freeMem[4] = {0};
    glGetIntegerv(GL_TEXTURE_FREE_MEMORY_ATI, &freeMem[0]);
    availableMemory = freeMem[0] / 1024;
    if(wglGetGPUInfoAMD(gpuIDs[0], WGL_GPU_RAM_AMD, GL_UNSIGNED_INT, sizeof(GLuint), &totalMemory) != 1)
    totalMemory = 0;
    if(wglGetGPUInfoAMD(gpuIDs[0], WGL_GPU_CLOCK_AMD, GL_UNSIGNED_INT, sizeof(GLuint), &clockSpeed) != 1)
    clockSpeed = 0;

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  14. poiuyTerry

    Here is the complete list of accepted parameters:

    The final two are particularly useful.
    The report on the total number of memory ‘evictions’ (swap outs) that have occurred since the last call.

    From NVidia specs:
    – dedicated video memory, total size (in kb) of the GPU memory

    – total available memory, total size (in Kb) of the memory
    available for allocations

    – current available dedicated video memory (in kb), currently unused GPU memory

    – count of total evictions seen by system

    – size of total video memory evicted (in kb)


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