Increasing Swap on a Raspberry Pi

In this guide, we will show you how to enable and increase the swap file on your Raspberry Pi.

The swap file is used to increase the system’s total accessible memory beyond its hardware capabilities.

This means that when all of the Raspberry Pi’s RAM is exhausted, it can start using the swap file as memory instead.

The addition of more virtual memory allows the system to deal with more memory intensive tasks without running into out of memory errors or having to shut down other additional packages.

However, the downside to this is that accessing the swap file is a significantly slower process that can create slowdowns.

The reason for this is that the swap file exists on your actual disk, which has significantly lower read and write speeds then your RAM.

Another caveat of a large swap file is that you need that space to be free on your SD Card. You can’t set a swap file on your Raspberry Pi larger than your available free space.

With the introduction of the Raspberry Pi 4, there has been less of a need to use a swap file due to the large amounts of RAM available.

Equipment

Below is the equipment that we used for this guide on increasing the size of the swap on the Raspberry Pi.

Recommended

• Raspberry Pi Amazon
• Micro SD Card Amazon
• Ethernet Cable Amazon  or Wi-Fi Amazon
• Power Supply Amazon

Optional

• Raspberry Pi Case Amazon
• USB Keyboard Amazon
• USB Mouse Amazon
• HDMI Cable Amazon
• Monitor Amazon

We last tested this tutorial on a Raspberry Pi 5 running the latest version of Raspberry Pi OS Trixie.

Increasing the Swap File on a Raspberry Pi

In this section, we will walk you through two methods to increase the size of the swap file on the Raspberry Pi.

Please note that the steps you take will differ depending on the Raspberry Pi OS release you are running. For those running Raspberry Pi OS Trixie or newer you will want to follow the “rpi-swap” instructions.

If you are running an older release you will need to follow our “dphys-swapfile” instructions instead.

Managing your Swap with rpi-swap

For those running Raspberry Pi OS Trixie or newer, the Pi uses a different service, rpi-swap, to manage the swap file on your system. This is meant to be a more modern, performance-friendly, and easier-to-use way to manage your swap.

For most users, rpi-swap will automatically create a decent-sized swap based on available space and your Raspberry Pi’s RAM. Of course, automatic is never perfect so them team still enables you to configure it yourself.

By default, the new rpi-swap service creates a swap file that follows these rules:

• The swap file has a maximum size of 2048MB
• It must not grow to more than 50 percent of the available disk space.
• The swap will be sized to be the same as the amount of RAM your Raspberry Pi has available as long as it doesnt exceed the previous two rules.
  
  This means if you had an 8GB Raspberry Pi with a 32GB SD Card, the largest swap that will be created by default is 2GB.
  
  Likewise, if you had a Raspberry Pi with only 1GB of RAM, the largest swap that the tool will generate with these rules is 1GB.

Controlling these rules to suite your own needs is relatively simple, and a process that we will cover over the next few steps.

1. The rpi-swap service has a lot of functionality baked into it, but we will be focusing on specifically controlling its swap file and setting the size it generates.

To override the default settings, we will want to create a new file within the “/etc/rpi/swap.conf.d” folder. Files created within this folder are read in by the service and used to overrwrite any of the default settings.

To ensure that this folder exists, we will first run the following command to create it.

sudo mkdir /etc/rpi/swap.conf.d/Copy

2. With the folder created, our next step is to create a new file in it. For this example, we will be naming ours “fixedswapsize.conf“. This makes it clear that we are using this override to set a fixed size for the swap file.

You can create this file and begin editing it by using the command below.

sudo nano /etc/rpi/swap.conf.d/fixedswapsize.confCopy

3. Now you can set the swap file size for your Raspberry Pi by entering the following two lines. The first line declares the configuration section, which in this case is the swap “file”.

The second line is what actually sets a fixed size for the swap file, this stops the automatic calculations from the “rpi-swap” tool and forces it to create a swap at that specific size.

Ensure that you swap out “<SWAPSIZE>” with the size of swap you want generated. Please note that this value is specified in mebibytes.

[File]
FixedSizeMiB=<SWAPSIZE>Copy

For example if you wanted to size your swap size to be 3 Gigabytes you would use the following.

[File]
FixedSizeMiB=3096Copy

4. After making these changes, you can save and quit out of the text edtior by pressing CTRL + X, Y, and then ENTER.

5. For the changes to your swap file size to properly take effect, you must restart your Rasbperry Pi.

You can easily restart your device by simply using the following command within the terminal.

sudo rebootCopy

6. Once your Raspberry Pi finishes booting, it should hopefully have created a brand new swap file that matches the size you specificed.

You can verify the swap has been properly created by using the following line.

ls -lh /var/swapCopy

If everything has worked correctly you should see something similar to what we have shown below. Of course your file size will differ depending on what you have set.

-rw------- 1 root root 3.1G Jan  7 20:51 /var/swap

Using dphys-swapfile to Manage your Swap

On older releases of Raspberry Pi OS, a different service was used to manage the swap file on your system.

If you are running an older release of Raspberry Pi OS such as Bookworm or older, then you will still be relying on the old “dphys-swapfile” service. This works completely different to the newer “rpi-swap” service, but is still fairly simple to use.

1. Before we can increase our Raspberry Pi’s swap file using dphys-swapfile, we must first temporarily stop it. The swap file cannot be in use while we increase it.

To stop the operating system from using the current swap file, run the following command.

sudo dphys-swapfile swapoff

2. Next, we need to modify the swap file configuration file.

We can open this file using nano by using the command below.

sudo nano /etc/dphys-swapfile

3. Within this config file, find the following line of text.

You can use CTRL + W to search for text within the file.

CONF_SWAPSIZE=100

To increase or decrease the swap file, all you need to do is modify the numerical value you find here.

This number is the size of the swap in megabytes.

For example, if we wanted to increase our swap size to 1GB, we would change that line to the following.

CONF_SWAPSIZE=1024

Whatever size you set, you must have that space available on your SD card.

4. Once you have made the change, save the file by pressing CTRL + X, followed by Y, then ENTER.

5. We can now re-initialize the Raspberry Pi’s swap file by running the command below.

Running this command will delete the original swap file and recreate it to fit the newly defined size.

sudo dphys-swapfile setup

6. With the swap now recreated to the newly defined size, we can now turn the swap back on.

To start the operating systems swap system, run the following command.

sudo dphys-swapfile swapon

While the new swapfile is now switched on, programs will not know that this new memory exists until they restart.

7. If you want all programs to be reloaded with access to the new memory pool, then the easiest way is to restart your device.

To restart your Raspberry Pi, all you need to do is run the command below.

sudo reboot

Conclusion

If you have got to this point in the tutorial you should now have successfully increased or decreased the size of the swap on your Raspberry Pi.

Newer versions of Pi operating system will have you using the newer and more useful “rpi-swap” service. Older versions will have you using “dphys-swapfile”. Both tools achieve the same thing, one just does a bit more helping along the swap.

Please feel free to leave a comment below if you have had any issues with this guide.

If you found this guide to be helpful, we recommend taking some time to explore some of our many Raspberry Pi projects.