Projector marketing is full of numbers designed to look impressive rather than inform. Understanding four core specs lets you see past the box and predict how a projector will actually look on your wall.
Resolution: native vs supported
Native resolution is the real, physical pixel grid of the imaging chip — it defines actual sharpness. Supported resolution only means the projector can accept that signal before scaling it down to the native panel. A projector that is "native 1080p, 4K support" is a Full HD projector; one that is "1080p support" is very often a 720p panel. Always buy on the native number.
Brightness: ANSI/ISO vs LED lumens
ANSI lumens (and the newer ISO 21118 standard) are measured, standardised figures for real screen brightness. "LED lumens" or "light source lumens" are theoretical and typically run three to five times higher than the equivalent ANSI figure — which is why a budget projector claims "9,000 lumens" yet a "3,800 ANSI" BenQ is far brighter in the room. Judge brightness only by ANSI or ISO lumens, and match it to your ambient light.
Light source: LED, DLP & laser
The light engine shapes both brightness and lifespan. LED lamps are affordable, run cool and last 30,000+ hours but are dimmer. DLP uses a micro-mirror (DMD) chip for crisp detail and strong contrast. Laser phosphor sources are the brightest and most colour-stable, lasting 20,000+ hours — and cost the most. Most budget home projectors are LED; picture-quality picks move to DLP or laser.
Throw, focus & keystone
The throw ratio tells you how far the projector sits from the wall for a given image size — a standard unit needs roughly 2.5–3m for a 100-inch picture, while short-throw models need far less. Auto focus sharpens the image and auto keystone squares it electronically when you're off-centre, so modern smart projectors set themselves up in seconds where older ones needed manual dials.