cvt

cvt [-r] [-v] [-d] width height [rate]

-r
    Use reduced vertical blanking (for DVI/HDMI/LCDs)

-v
    Verbose output showing CVT calculations

-d
    Dump timings as decimal values (no fractions)

width
    Horizontal resolution in pixels (required)

height
    Vertical resolution in pixels (required)

rate
    Refresh rate in Hz (optional, defaults to 60)

The cvt command, part of the Xorg utilities, calculates Modeline entries using the VESA CVT (Coordinated Video Timings) standard. It produces timings optimized for modern flat-panel displays, projectors, and DVI/HDMI outputs, especially with reduced blanking to lower pixel clock rates.

Primarily used to create custom video modes not available in X11's built-in timings. Output includes a complete Modeline string and Option line, ready for xrandr (e.g., xrandr --newmode "mode" values; xrandr --addmode output "mode") or xorg.conf Section "Monitor".

Specify desired resolution and optional refresh rate. Ideal for LCDs where GTF timings (from gtf) may cause issues like washed-out blacks or sync problems. Supports rates from ~25Hz to 500Hz, but hardware limits apply. Verbose mode details calculations; decimal dump aids scripting.

Enhances flexibility in multi-monitor setups or high-res displays without recompiling Xorg.

Timings may need hardware verification; not all GPUs/support reduced blanking; high rates increase EMI/noise risks.
Deprecated in Wayland; use xrandr or kernel modesetting.

cvt 1920 1080 60
# 1080x1920 59.96 Hz (CVT) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync

Copy modeline, then:
xrandr --newmode "1920x1080_60.00" 173.00 ...
xrandr --addmode HDMI-1 "1920x1080_60.00"
xrandr --output HDMI-1 --mode "1920x1080_60.00"

Introduced in Xorg 6.9 (2005) to implement VESA CVT 1.1 (2003), superseding GTF for flat panels. Maintained in xorg-app package; minor updates for CVT 1.2 support.

gtf(1), xrandr(1), fbset(1)