Lux to Phots Converter
Enter the illumination in lux below to convert it to phots.
Convert Lux to Phots
Enter a value in lux (lx) to convert to phots (ph).
Lux to Phot Conversion Table
Table showing various lux measurements converted to phots. Click any preset value or arrow to load it into the converter.
How to Convert Lux to Phots
To convert lux to phots, multiply the illumination by the following conversion ratio: 0.0001 phots/lux.
Since one lux is equal to 0.0001 phots, you can use this simple formula to convert:
The illumination in phots is equal to the illumination in lux multiplied by 0.0001.
For example, here's how to convert 5 lux to phots using the formula above.
How Many Phots Are in a Lux?
There are 0.0001 phots in a lux, which is why we use this value in the formula above.
Our lux to phot calculator automatically converts your illumination measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Lux and phots are both units used to measure illumination. Keep reading to learn more about each unit.
What Is a Lux?
SI derived unit of illuminance (1 lumen per square meter). It serves as a primary reference unit for measuring illumination across scientific and practical applications. [1]
The lux is classified as an International System of Units (SI) unit of illumination. Lux can be abbreviated as lx; for example, 1 lux can be written as 1 lx.
As the primary coherent reference unit for illumination in this category, all other illumination units are mathematically anchored to the lux (lx).
In practice, lux (lx) are widely used across standard illumination applications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
What Is a Phot?
A phot is a unit of illumination equal to 10,000 lux (lx), the base unit for illumination. CGS illuminance unit equal to 10,000 lux. [2]
The phot is classified as a metric and SI-compatible unit of illumination. Phots can be abbreviated as ph; for example, 1 phot can be written as 1 ph.
When working with phots (ph) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, phots (ph) are widely used across large-scale industrial, bulk, and macro-level illumination specifications within SI metric workflows, engineering documentation, and technical data sheets.
When converting illumination between lux (lx) and phots (ph), keep full floating-point precision (1 lx = 0.0001 ph; 1 ph = 10,000 lx) during intermediate calculations and round only the final phot figure to match your instrument tolerance.
More Lux & Phot Conversions
Need to calculate in the opposite direction? Use our phots to lux calculator to switch your starting unit immediately. You can also explore related tools such as converting phots to lux, converting lux to kilolux, or converting lux to millilux.
Convert from Lux
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Length)·Illumination Metrology Standard — Lux (lx) to Phots (ph)
- [2]BIPM SpecificationBIPM (SI Base Unit: Metre (m))·Unit Specifications: Lux (lx) & Phot (lm/cm²) (ph)
- [3]NIST HB 133 ReferenceNIST HB 133 (NIST Handbook 133 (2019 Ed.))·Conversion Factors & Mathematical Basis (lx to ph)