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Overview

By default, niri will attempt to turn on all connected monitors using their preferred modes. You can disable or adjust this with output sections. 
output "eDP-1" {
    mode "[email protected]"
    scale 2.0
    transform "90"
    position x=1280 y=0
    variable-refresh-rate
}

output "HDMI-A-1" {
    mode "[email protected]"
}
Outputs are matched by connector name (i.e. eDP-1, HDMI-A-1), or by monitor manufacturer, model, and serial, separated by a single space each.

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Finding Output Names

You can find all output information by running: 
niri msg outputs
Usually, the built-in monitor in laptops will be called eDP-1.
The output name is case-insensitive. Outputs can be matched by manufacturer, model, and serial. Before, they could be matched only by the connector name.

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Basic Settings

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Disable Output

This flag turns off that output entirely. 
// Turn off that monitor.
output "HDMI-A-1" {
    off
}

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Mode

Set the monitor resolution and refresh rate.
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mode
string
Format: <width>x<height> or <width>x<height>@<refresh rate>If the refresh rate is omitted, niri will pick the highest refresh rate for the resolution.
// Set a high refresh rate for this monitor.
output "HDMI-A-1" {
    mode "[email protected]"
}

// Use a lower resolution on the built-in laptop monitor
output "eDP-1" {
    mode "1280x720"
}
The refresh rate that you set here must match exactly, down to the three decimal digits, to what you see in niri msg outputs.
You can configure a custom mode (not offered by the monitor) by setting custom=true. In this case, the refresh rate is mandatory.
output "HDMI-A-1" {
    mode custom=true "[email protected]"
}
Custom modes are not guaranteed to work and may damage your monitor, especially if it’s a CRT. Use at your own risk. Follow the maximum supported limits in your monitor’s instructions.

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Modeline

Directly configures the monitor’s mode via a modeline, overriding any configured mode. The modeline can be calculated via utilities such as cvt or gtf. 
output "eDP-3" {
    modeline 173.00  1920 2048 2248 2576  1080 1083 1088 1120 "-hsync" "+vsync"
}
Out of spec modelines may damage your monitor, especially if it’s a CRT. Follow the maximum supported limits in your monitor’s instructions.

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Scale

Set the scale of the monitor.
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scale
number
default:"auto"
Scale factor for the output. Can be integer or fractional (e.g., 1.5 for 150% scale). If unset, niri will guess an appropriate scale based on the physical dimensions and resolution.
output "eDP-1" {
    scale 2.0
}
  • You can use fractional scale values, for example scale 1.5
  • Dot is no longer needed for integer scale: scale 2 instead of scale 2.0
  • Scale below 0 and above 10 will fail during config parsing

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Transform

Rotate the output counter-clockwise.
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transform
string
default:"normal"
Valid values: normal, 90, 180, 270, flipped, flipped-90, flipped-180, flipped-270Values with flipped additionally flip the output.
output "HDMI-A-1" {
    transform "90"
}

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Position

Set the position of the output in the global coordinate space. 
output "HDMI-A-1" {
    position x=1920 y=0
}
Output scale and rotation has to be taken into account for positioning: outputs are sized in logical, or scaled, pixels.For example, a 3840×2160 output with scale 2.0 will have a logical size of 1920×1080, so to put another output directly adjacent to it on the right, set its x to 1920.
This affects:
  • Directional monitor actions like focus-monitor-left
  • Cursor movement (cursor can only move between directly adjacent outputs)

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Automatic Positioning

If the position is unset or results in an overlap, the output is placed automatically using this algorithm:
  1. Collect all connected monitors and their logical sizes
  2. Sort them by their name (makes positioning deterministic)
  3. Try to place every output with explicitly configured position, in order
  4. Place every output without explicitly configured position by putting it to the right of all previously placed outputs

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Advanced Settings

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Variable Refresh Rate

This flag enables variable refresh rate (VRR, also known as adaptive sync, FreeSync, or G-Sync), if the output supports it. 
output "HDMI-A-1" {
    variable-refresh-rate
}
You can check whether an output supports VRR in niri msg outputs.
Some drivers have various issues with VRR:
  • If the cursor moves at a low framerate with VRR, try setting the disable-cursor-plane debug flag
  • If a monitor is not detected as VRR-capable when it should, sometimes unplugging a different monitor fixes it
  • Some monitors will continuously modeset (flash black) with VRR enabled
You can set the on-demand=true property, which will only enable VRR when this output shows a window matching the variable-refresh-rate window rule.
output "HDMI-A-1" {
    variable-refresh-rate on-demand=true
}
This is helpful to avoid various issues with VRR, since it can be disabled most of the time, and only enabled for specific windows, like games or video players.

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Focus at Startup

Focus this output by default when niri starts. 
// Focus HDMI-A-1 by default.
output "HDMI-A-1" {
    focus-at-startup
}

// ...if HDMI-A-1 wasn't connected, focus DP-2 instead.
output "DP-2" {
    focus-at-startup
}
If multiple outputs with focus-at-startup are connected, they are prioritized in the order that they appear in the config.When none of the connected outputs are explicitly focus-at-startup, niri will focus the first one sorted by name.

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Backdrop Color

Set the backdrop color that niri draws for this output. This is visible between workspaces or in the overview. 
output "HDMI-A-1" {
    backdrop-color "#001100"
}
The alpha channel for this color will be ignored.

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Hot Corners

Customize the hot corners for this output. By default, hot corners in the gestures settings are used for all outputs. 
// Enable the bottom-left and bottom-right hot corners on HDMI-A-1.
output "HDMI-A-1" {
    hot-corners {
        bottom-left
        bottom-right
    }
}

// Disable the hot corners on DP-2.
output "DP-2" {
    hot-corners {
        off
    }
}
Hot corners toggle the overview when you put your mouse at the very corner of a monitor.

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Layout Config Overrides

You can customize layout settings for an output with a layout {} block: 
output "SomeCompany VerticalMonitor 1234" {
    transform "90"

    layout {
        default-column-width { proportion 1.0; }
        // ...any other layout setting
    }
}

output "SomeCompany UltrawideMonitor 1234" {
    layout {
        default-column-width { proportion 0.25; }

        preset-column-widths {
            proportion 0.2
            proportion 0.25
            proportion 0.5
            proportion 0.75
            proportion 0.8
        }
    }
}
It accepts all the same options as the top-level layout {} block.
In order to unset a flag, write it with false:
layout {
    // Enabled globally.
    always-center-single-column
}

output "eDP-1" {
    layout {
        // Unset on this output.
        always-center-single-column false
    }
}

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