Semi-cutoff luminaires emit between 0 and 31% of the luminous flux above the horizon. There are further criteria.
- Above the horizon: Luminous intensity (in candelas) must be less than 5% of the total luminous flux (in lumens).
- Glare zone: Luminous intensity (in candelas) must be less than 20% of the total luminous flux (in lumens).
A semi-cutoff luminaire of 1,000 lm, for example, can emit up to 50 candelas in all lateral angles above the horizon and less than 200 candelas in all lateral angles in the glare zone.