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06 Numbers and Powers

System Error Memory Dump Files: What They Are

Card No. 06·1358 · Updated · Standard formula, shown below

Estimated file size 16.00 GB
Total RAM (GB)
16 GB
You entered
Dump type
Automatic
You entered
You enter
Total RAM (GB), Dump type
You get
Estimated file size
Rounding
2 dp

System error memory dump files are files Windows automatically creates when the system crashes (the Blue Screen of Death), containing a snapshot of memory at the moment of the crash. They are used to diagnose the cause of the error, and this page explains what each type contains, where they are stored, and how to manage them.

Formula

The estimated file size of a memory dump is roughly proportional to the amount of RAM in your system, multiplied by a factor that depends on the dump type:

  • Automatic or Kernel dump: about 100% of RAM (the kernel and loaded drivers are usually a large fraction of physical memory).
  • Complete dump: exactly the size of RAM (plus a small header).
  • Small dump (minidump): 256 KB (0.25 GB) regardless of RAM.
  • Active dump: similar to kernel, but excludes irrelevant memory pages.

The calculator uses the formula: file_size = RAM × factor, where the factor is 1 for most types, 0.25 for small dumps. The result is in GB, rounded to two decimals.

Worked Example

With the default values (16 GB RAM, Automatic dump type):

  1. Factor = 1 (Automatic).
  2. File size = 16 GB × 1 = 16 GB.
  3. Result: 16.00 GB.

That means a crash on a 16 GB system with an automatic dump will likely create a file around 16 GB on your system drive.

What Are Memory Dump Files?

When Windows encounters a fatal error (a “bug check� or BSOD), it stops the system and writes a memory dump file. This file contains the contents of RAM (or a portion of it) at the moment of the crash, along with the list of loaded drivers and the error code. Developers and advanced users analyze these files to identify which driver or component caused the crash.

There are five main types, each with a different size and purpose:

  • Small memory dump (minidump) – 256 KB, stored in C:\Windows\Minidump. Contains the error code, parameters, list of loaded drivers, and the processor context of the crashed thread. Enough for basic analysis.
  • Kernel memory dump – stores only kernel-mode memory, usually a few hundred MB to a few GB. Stored in C:\Windows\Memory.dmp.
  • Automatic memory dump – same as kernel, but Windows can choose to create a smaller file if the page file is too small. This is the default.
  • Complete memory dump – contains all of physical memory, so the file is exactly the size of RAM. Requires a page file at least as large as RAM.
  • Active memory dump – similar to complete but excludes memory that is not relevant to the crash (e.g., user pages that are not part of the problem).

Where Are They Stored?

By default, small dumps go to C:\Windows\Minidump, while kernel, automatic, complete, and active dumps go to C:\Windows\Memory.dmp. The location can be changed via System Properties → Advanced → Startup and Recovery Settings. You can also choose to overwrite the existing dump file or create a new one each time.

How to Read a Dump File

You can’t open a dump file with a text editor; it’s a binary file. To analyze it, you need debugging tools:

  • WinDbg – a free tool from Microsoft (part of the Windows SDK). Open the dump file and run !analyze -v to get the bug check code and the likely culprit driver.
  • BlueScreenView – a free third-party tool that reads minidumps and shows a summary of the crash, including the driver that caused it.

For most users, the easiest way is to use BlueScreenView, which extracts the essential info without requiring deep debugging skills.

Common Problems and Misconceptions

  • My disk is full because of dump files. Yes, a complete dump on a 32 GB system can be 32 GB. You can safely delete C:\Windows\Memory.dmp and the Minidump folder if you don’t need them for debugging. Windows will recreate them on the next crash.
  • Dump files cause crashes. No, they are a symptom, not a cause. They are written after the crash to help diagnose it.
  • I don’t have a page file, so no dump is created. Correct. To create a kernel or complete dump, Windows needs a page file on the system drive (usually C:) that is at least as large as RAM (for complete) or a certain size (for kernel). If you have no page file, you’ll see a message like “No dump file was generatedâ€�.
  • Small dumps are always enough. For most BSODs, a minidump is sufficient to identify the faulty driver. But if the problem is subtle, a kernel dump may be needed.

How to Delete or Disable Dump Files

If you’re short on disk space, you can safely delete dump files. To disable them entirely, go to System Properties → Advanced → Startup and Recovery Settings, and under “Write debugging information� choose “(none)�. This prevents future dumps from being created, but it also means you lose the diagnostic information if a crash occurs.

Frequently Asked Questions

Can I delete Memory.dmp?

Yes. It’s only used for debugging. If you don’t plan to analyze the crash, deleting it frees up space. Windows will create a new one next time it crashes (if the setting is enabled).

Why is my dump file so large?

Because it contains a copy of your RAM (or kernel memory). On a system with 32 GB of RAM, a complete dump is about 32 GB. Automatic dumps are usually smaller but still proportional to RAM.

What is the difference between a minidump and a complete dump?

A minidump is only 256 KB and contains just the essential info (error code, drivers, thread context). A complete dump contains all of physical memory, which is much larger but provides a full picture of the system state.

How do I open a .dmp file?

Use a debugging tool such as WinDbg (free from Microsoft) or a third-party tool like BlueScreenView. You cannot open it with Notepad.

Do dump files slow down my computer?

No. They are only written at the moment of a crash, which is already a failure state. They don’t run in the background or consume resources during normal operation.

Will deleting dump files fix my BSOD?

No. The dump file is a record of the crash, not the cause. Deleting it doesn’t fix the underlying problem. You need to analyze the dump to find the faulty driver or hardware.

Related

Formula used
in size | Total RAM (GB) | GB | 16 | 1 | 2048
sel type | Dump type | Automatic=1, Kernel=1, Complete=1, Small=0.25, Active=1
out file | Estimated file size | GB | size * type | 2

Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.

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