UK What VGA means
VGA, short for Video Graphics Array, is an analogue video standard that IBM introduced in 1987 with its PS/2 computers. The name first described a graphics mode of 640 × 480 pixels, but it soon came to mean the blue 15-pin connector that carried it, and the connector outlived the mode by decades.
VGA was the standard monitor connection on PCs for around 20 years, until DVI, HDMI and DisplayPort replaced it on consumer equipment. It remains common in industry, because machines and control systems built around it are still in service and many replacement monitors are expected to plug straight in.
How the VGA connector works
The VGA connector is a DE-15 D-sub plug, often called HD15, with 15 pins in three rows of five and two thumbscrews that hold it in place. It carries three kinds of signal.
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Red, green and blue. Three separate analogue signals, each on its own 75 ohm line, set the brightness of each colour as the image is drawn line by line.
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Horizontal and vertical sync. Two timing signals tell the monitor when each line and each frame starts, which is how it works out the resolution and refresh rate.
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DDC. The VESA Display Data Channel lets the computer read the monitor’s EDID data, so it can pick a supported resolution automatically.
VGA resolutions
Because the signal is analogue, VGA has no fixed maximum resolution. The limit is set by the graphics output, the cable and the monitor. In practice, VGA carries up to 1920 × 1080 or 1920 × 1200 at 60 Hz cleanly over a good cable of a few metres, and higher on some equipment. The resolution names below all date from the VGA era and are still used to describe industrial panels.
| Name | Resolution | Aspect ratio | Where you see it today |
|---|---|---|---|
| VGA | 640 × 480 | 4:3 | Small instrument and handheld screens |
| SVGA | 800 × 600 | 4:3 | 7 and 8 inch panels |
| XGA | 1024 × 768 | 4:3 | 10.4, 12.1 and 15 inch industrial monitors |
| SXGA | 1280 × 1024 | 5:4 | 17 and 19 inch industrial monitors |
| UXGA | 1600 × 1200 | 4:3 | Larger 4:3 control and medical displays |
| WUXGA | 1920 × 1200 | 16:10 | Widescreen monitors, the practical VGA ceiling |
Picture quality falls as resolution and cable length rise. The analogue signal picks up noise and loses sharpness, which shows as blur, ghosting or a slight shimmer. At XGA and SXGA, VGA usually looks fine; at full HD on a long run, a digital link is clearly sharper. Most monitors have an auto-adjust button that realigns the image to the analogue signal when it looks soft or shifted.
VGA vs HDMI
HDMI replaced VGA on most new equipment because it is digital: each pixel arrives exactly as the computer drew it, so the picture stays sharp at full HD and beyond, and the monitor does not need adjusting for position or phase. HDMI also carries audio and supports HDCP for protected content. VGA’s advantages are narrower but real in industry: it works with decades of existing equipment, the thumbscrews hold the plug in place, and an analogue signal that degrades gradually is sometimes easier to diagnose than a digital link that simply drops out.
Converting VGA to HDMI
VGA is analogue and HDMI is digital, so the two cannot be joined with a simple cable. Cables sold with a VGA plug on one end and HDMI on the other only work if they contain conversion electronics, which is usually a small box in the lead.
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VGA to HDMI. Needs an active converter that digitises the analogue signal. These usually take power from a USB port and have a 3.5 mm audio input, because VGA carries no sound.
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HDMI to VGA. Also active, but the converter is often small enough to sit in the plug and run from the HDMI port’s own power.
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DVI-I to VGA. Works with a passive adapter, because DVI-I carries the same analogue signals on extra pins.
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VGA into a computer. To record or analyse a VGA output rather than display it, a capture card digitises it directly, which removes the separate converter.
Where VGA is still used in industry
VGA survives where equipment lasts longer than consumer electronics. CNC machine controllers, older PLC operator panels, ultrasound and laboratory instruments, and many test sets still output VGA, and replacing the machine to change the connector is rarely worth it. Long qualification cycles in medical, defence and process plants keep these outputs in service even longer.
That is why most of our industrial monitors still have a VGA input alongside HDMI or DisplayPort, and why our 4:3 industrial monitors are often specified to replace old screens on legacy machines without changing the controller. Many of our embedded box PCs also keep a VGA output for the same reason. To bring a legacy VGA output into a modern system for recording or AI inspection, our VGA capture cards digitise it inside the computer.
Quick answers on VGA
VGA: common questions
Is VGA analogue or digital?
Analogue. VGA sends the image as varying voltages for red, green and blue. DVI, HDMI and DisplayPort are digital.
Does VGA carry audio?
No. VGA is video only, so sound needs a separate cable, usually a 3.5 mm audio lead.
Can you connect VGA to HDMI without a converter?
No. The signals are different, so a plain cable cannot work. A VGA to HDMI converter with its own power is needed.
Is VGA worse than HDMI?
At high resolutions, yes. HDMI is digital, carries audio and stays sharp at full HD and above. At XGA or SXGA on a short cable, the difference is small.
Is VGA still used?
Yes, mainly on industrial and legacy equipment. It has largely disappeared from consumer laptops and TVs but remains common on industrial monitors, embedded computers and machine controllers.
We specify the monitors, converters or capture cards that suit your legacy VGA equipment and test the connection as standard, so older machines keep running alongside new systems.