Sports Lighting Glare Indices Compared: GR (ANSI/IES) vs UGR (CIE)
An engineering reference for facility designers and lighting engineers comparing the two primary sports lighting glare indices: GR (Glare Rating per ANSI/IES) and UGR (Unified Glare Rating per CIE). Covers when each is used, how they relate, and which to specify for US sports lighting projects.
Sports lighting glare quantification uses two related but distinct indices. GR (Glare Rating per ANSI/IES) is the US standard, referenced in IES RP-6. UGR (Unified Glare Rating per CIE) is the European and international standard, referenced in FIFA, FIBA, and World Athletics specifications. They are not directly interchangeable, and projects with international sanctioning may need both calculated.
GR (ANSI/IES Glare Rating)
GR is the US sports lighting glare index per ANSI/IES standards, calculated from fixture luminance, angular position, background luminance, and solid angle subtended. It produces a numeric value typically 20–80, with lower indicating less glare.
GR Range | Subjective Glare |
< 30 | Imperceptible (broadcast tier) |
30–40 | Acceptable for highest-tier broadcast |
40–50 | Acceptable for general competition |
50–60 | Borderline (recreational only) |
> 60 | Disturbing (non-compliant) |
UGR (CIE Unified Glare Rating)
UGR is the European / international glare index per CIE standards, used in FIFA, FIBA, and World Athletics specifications. UGR is typically 10–30, with lower indicating less glare.
UGR Range | Subjective Glare |
< 16 | Imperceptible (broadcast tier) |
16–19 | Acceptable for FIFA / FIBA broadcast |
19–22 | Acceptable for general competition |
22–25 | Borderline (recreational only) |
> 25 | Disturbing (non-compliant) |
Approximate Conversion Between GR and UGR
GR and UGR don’t convert exactly because the formulas use different luminance reference frames and weighting. Approximate mapping for sports lighting:
Tier | GR Target | UGR Equivalent |
Highest broadcast (FIFA, MLB, NCAA D-I FBS) | < 30 | < 16 |
Standard broadcast (NCAA D-I FCS, MiLB) | 30–40 | 16–19 |
General competition (HS varsity, NCAA D-II/III) | 40–50 | 19–22 |
Recreational | 50–60 | 22–25 |
For US sports lighting projects, GR is the standard. For projects with international sanctioning (FIFA, FIBA, World Athletics, ICC), specify both GR and UGR in the photometric study.
For broader Glare Rating methodology, see Glare Rating (GR) for Sports Lighting. For international sanctioning standards, see International Sports Lighting Standards.
Specifying glare for an international-tier venue? Request a free 24–48 hour AGi32 photometric study with GR and UGR calculations →
Frequently Asked Questions
What's the difference between GR and UGR?
GR (Glare Rating per ANSI/IES) is the US sports lighting glare index, used in IES RP-6 specifications. UGR (Unified Glare Rating per CIE) is the European / international glare index, used in FIFA, FIBA, and World Athletics specifications. They are not directly interchangeable; formulas use different luminance reference frames and weighting.
What GR target does NCAA D-I FBS broadcast require?
GR < 30 (imperceptible glare tier) for NCAA D-I FBS, MLB, FIFA, FIBA Level 1 broadcast venues. NCAA D-I FCS and MiLB broadcast: GR 30–40. HS varsity and NCAA D-II/III: GR 40–50. Recreational: GR 50–60. Above 60 is non-compliant with IES RP-6.
Should I specify GR or UGR for a US sports lighting project?
GR is the US standard, referenced in IES RP-6. For US-only projects, specify GR. For projects with international sanctioning (FIFA Cat A/B/C, FIBA Level 1/2, World Athletics Class I/II, ICC international), specify both GR and UGR in the photometric study to support both US and international compliance documentation.
How is GR calculated?
GR per ANSI/IES standards uses fixture luminance, angular position in the viewer’s field, background luminance, and solid angle subtended by each fixture from the viewing position. Calculated automatically by AGi32 / DIALux from photometric model. Calculated at viewing positions across the playing area (player eye height, broadcast camera positions).
What's a typical UGR target for FIFA Category A broadcast?
FIFA Category A (World Cup, top-tier broadcast): UGR < 16. FIFA Category B (UEFA Champions League): UGR < 19. FIFA Category C (national team): UGR < 22. FIBA Level 1 (Olympic, World Cup): UGR < 16. World Athletics Class I (Olympic, World Championship): UGR < 16.
Can the same Duvon fixtures meet both GR and UGR targets?
Yes. Apex Series (broadcast tier) consistently delivers GR 25–32 / UGR 14–17 in international-sanctioning installations. Vanguard Series delivers GR 30–38 / UGR 17–19 for NCAA / USL / FIFA Cat C. Liberty Series delivers GR 35–42 / UGR 19–22 for HS varsity and NCAA D-II/III. Duvon photometric studies include both GR and UGR calculations for projects with international sanctioning requirements.