ANSI vs ISO vs LED lumens
Not all lumen ratings are equal. ANSI, ISO 21118, CVIA, LED and marketing lumens compared — which to trust when sizing a projector.
ANSI and ISO 21118 lumens are measured the same trustworthy way (averaged across the image) and are roughly equal. CVIA is a reliable newer standard. "LED lumens" and vague "marketing lumens" are inflated — often 2 to 3 times the real ANSI figure. Always size brightness by the ANSI or ISO number.
A lumen rating only means something if you know how it was measured. The honest standards (ANSI, ISO 21118, CVIA) average the light actually landing on the screen. Inflated figures like "LED lumens" measure the raw source or a peak, so a "700 LED lumen" projector might be ~250 ANSI. When two projectors quote different units, convert mentally to ANSI before comparing.
Projector lumen standards compared
| Standard | How it is measured | Reliability |
|---|---|---|
| ANSI lumens | Averaged over 9 screen points | Trusted industry standard |
| ISO 21118 | Stricter 9-point method | Trusted, ~ANSI |
| CVIA lumens | Calibrated Chinese standard | Fairly reliable |
| LED / source lumens | Light at the source, not the screen | Inflated — 2-3x high |
| "Marketing" lumens | Unspecified or peak | Unreliable |