Ever noticed the label of your bulb carefully? You may have noted that its light output is displayed in ‘lumens.’
Key Takeaways
- Lumen is a unit of measurement for the total amount of visible light emitted by a light source; ANSI lumen is a standardized measurement for projector brightness developed by the American National Standards Institute (ANSI).
- ANSI lumen measurement follows a specific testing protocol, ensuring consistent and comparable results across different projector models; lumen measurements may vary depending on the testing conditions or methodology.
- When comparing projectors, ANSI lumen values provide a more reliable brightness indicator than generic ones.
Lumen vs. ANSI Lumen
Lumen and ANSI Lumen are both units of measurement used to describe the brightness of a light source, such as a projector or bulb. Lumen is an SI unit, a measure of the source’s luminous flux or total energy. ANSI Lumen measures the amount of light that reaches the screen or surface. ANSI Lumen is a more accurate measurement.
Lumen (lm) is the SI unit for measurement of luminous flux, i.e., the intensity (in candela) of light emitted per solid angle. ANSI lumen is also used to measure luminous flux but is standardized by the American National Standards Institute.
The reason for introducing a new unit in the form of ANSI lumens is that it provides a more realistic brightness measurement since it is well structured and based on a greater number of experimental values.
Comparison Table
| Parameter of Comparison | Lumen | ANSI Lumen |
|---|---|---|
| Symbol | The symbol for lumen is ‘lm’ | ANSI lumen does not have any specific symbol |
| System of units | Lumen is the unit of luminous flux under the SI system of units | ANSI lumen is not an SI unit for measuring luminous intensity |
| Standardization | ANSI does not standardize it | The American National Standards Institute standardizes it |
| Accuracy | It is less specific and accurate than the ANSI lumen | It is more specific and accurate than lumen since it is based on a greater no. of experimental values. |
| Applications | It is used for rating lamps and light bulbs | It is used for displaying the light output of projectors |
What is Lumen?
Lumen s derived from the Latin word lumin meaning light. It is the standard unit for measuring the amount of light intensity across a solid angle of one steradian, i.e., it measures luminous flux. Its symbol is ‘lm.’
1 lm = 1 cd x sr
(cd-calendula: SI unit to measure light intensity
sr-steradian: SI unit to measure solid angle)
Since 2010, lighting equipment has been labeled primarily luminous flux (in lumens, lm) as an alternative to electrical power (in watts, W).
The more lux (for constant lumens), the farther the reach of the light from the source. On the other hand, the more the lumens (for constant lux), the more the brightness of light through a given area.
What is ANSI Lumen?
ANSI Lumens is another unit for measuring luminous flux and is assigned by ANSI-American National Standards Institute, but I am not an SI unit. It finds applications majorly in the rating of projectors.
For commercial purposes, the projectors that undergo this procedure have their luminous flux quoted in ANSI lumens.
Method for measuring ANSI lumens for projectors: The projector’s light output is recorded at nine points around the screen, then its average is calculated.
The product of the average value with the screen’s area gives the projector’s brightness in ANSI lumens. The specification for the ANSI lumen measurement of projectors does not depend on the projected image size.
Major Differences Between Lumen and ANSI Lumen
- Lumen is the SI unit for measuring luminous flux to rate the light output of an artificial light source, Whereas ANSI lumen is not an SI unit.
- ANSI lumen is described and structured by the American National Standards System, which also has a specific procedure to measure the luminous flux, but the lumen is not standardized by the ANSI
- https://iopscience.iop.org/article/10.1088/0026-1394/11/3/001/meta
- https://www.spiedigitallibrary.org/conference-proceedings-of-spie/2650/0000/New-ANSIIEC-standard-for-projectors/10.1117/12.237015.short
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
