VYSN

CRI – Colour Rendering for LED Luminaires

What is the CRI value and why does it matter for LED?

The CRI (Colour Rendering Index), also called Ra value, describes how naturally colours are rendered under a light source. The scale ranges from 0 to 100, where 100 corresponds to the reference source (incandescent/daylight). For professional lighting: CRI≥80 is mandatory per DIN EN 12464-1 for most workplaces. CRI≥90 is recommended for areas with colour assessment (printing, textiles, retail, medical practices). CRI≥95 is standard for museum lighting and photo studios. CRI is particularly important for LED luminaires because the light spectrum of LEDs fundamentally differs from incandescent lamps.

CRI Requirements by Application

CRI ≥60 (Minimum): Parking garages, storage rooms without visual tasks, outdoor path lighting. CRI ≥80 (Standard): Offices, workshops, production halls, schools, hospitals (general), hospitality, residential. CRI ≥90 (High): Retail (fashion, food), printing, textile industry, medical practices (examination rooms), hair salons, art galleries. CRI ≥95 (Premium): Museums, photo studios, colour sample evaluation, operating theatres, dental practices. Rule of thumb: When in doubt, choose CRI 90. The price difference to CRI 80 for modern LEDs is only 5-15%, but light quality is visibly better.

CRI 80 vs. CRI 90: The Visible Difference

At CRI 80, most colours are rendered acceptably, but saturated reds (R9 value) often appear pale or brownish. Skin tones can look unnatural. At CRI 90+, all colours are noticeably more natural, reds vivid and skin tones healthy. The R9 value (red saturation) is particularly critical: Many CRI-80 LEDs have R9 of only 0-20, while CRI-90 LEDs typically achieve R9>50. For meat counters, fashion retail and medical lighting, a high R9 is essential. Tip: Pay attention not only to the Ra value (average over 8 test colours), but also R9 (saturated red) and R13 (skin colour).

Related Products

LED Recessed Downlights →Office Lighting →

FAQ

Is CRI 80 enough for an office?+

Yes, CRI≥80 meets DIN EN 12464-1 for offices. For a pleasant working atmosphere, we still recommend CRI 90, especially in areas where people collaborate (meeting rooms, reception). Skin tones appear more natural at CRI 90.

Why do some LED luminaires have CRI>95 but poor reds?+

The Ra value (CRI) is the average over 8 test colours (R1-R8). Saturated red (R9) is not included in this calculation. A high Ra can therefore still have a low R9. When selecting, pay attention to the separately stated R9 value, especially for applications where reds matter.

Does a higher CRI affect energy efficiency?+

Yes, slightly. To produce a broader colour spectrum (higher CRI), LED chips sacrifice some efficiency. Typically: CRI 80 LEDs achieve 140-160 lm/W, CRI 90 LEDs approx. 120-140 lm/W, CRI 95+ approx. 100-120 lm/W. The efficiency loss from CRI 80 to 90 is only approx. 10-15% and is negligible in most applications.

What is the difference between CRI and TM-30?+

CRI/Ra is based on only 8 (or 14) test colours and was developed in the 1960s. TM-30 (IES) is a more modern system with 99 test colours offering more detailed information about colour fidelity and saturation. TM-30 gives two values: Rf (Fidelity, similar to CRI) and Rg (Gamut, colour saturation). In practice, CRI is still most commonly used and referenced in standards. TM-30 is gaining importance in lighting design.

Related Articles

DIN EN 12464-1 – Workplace Lighting

DIN EN 12464-1 requirements: Lux values, UGR limits, colour rendering for office, industry, workshops. Overview table and practical tips for electricians.

UGR – Glare Rating for Luminaires

What is the UGR value? Glare rating per DIN EN 12464-1 explained. UGR<19 for offices, UGR<22 for industry. Table, calculation and practical tips for electricians.

Lux – Planning Illuminance Correctly

How many Lux for an office, workshop, warehouse? Lux table per DIN EN 12464-1, calculation formula and practical examples for electricians.

CRI Value Explained: Colour Rendering in LED Lighting | VYSN Lighting