What problem this solves
Color temperature is the second most-specified lamp parameter (after wattage) and the most commonly misunderstood. Designers specify 3000K “for warmth” not realizing it suppresses melatonin in the evening, hurting sleep; or specify 5000K in a living room chasing a “modern” look and finding it reads clinical. The Kelvin number alone hides the effects. This tool surfaces them.
Who it’s for
- Designers specifying fixtures for hospitality and residential projects
- Homeowners replacing bulbs who want a quick sanity check
- Anyone building a circadian-friendly home lighting plan
How to interpret the result
The mood label reflects how the room feels in interior photography and on-site, not just how the colorimetry describes it. The circadian line tells you how much blue-light content reaches the eye — the predictor of melatonin suppression. CRI (Color Rendering Index) is wavelength-dependent, so warm-white LEDs at 2700K often render reds poorly unless they’re labeled high-CRI (90+).
Limitations
- CRI is averaged across 8 reference colors — TM-30 (Rf/Rg) is more accurate but rarely on packaging
- Perceived warmth is also driven by lux (brightness); a dim 4000K reads warmer than a bright one
- Dim-to-warm lamps shift Kelvin when dimmed — the 2700K spec is at full brightness only
- Individual circadian sensitivity varies up to 5× between people