Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Phot to Lux
Convert ph to lx instantly, then review the formula, assumptions, and rounding guidance.
Light & sound unitsInstant result
Decimals
Formula result = input × 10000 ÷ 1. 1 ph = 10,000 lx
Common examples
One value, several units
Lux10,000 lx
Foot-candles929.0304 fc
Nox10,000,000 nx
Conversion table
| ph | lx |
|---|---|
| 1 ph | 10,000 lx |
| 2 ph | 20,000 lx |
| 5 ph | 50,000 lx |
| 10 ph | 100,000 lx |
| 25 ph | 250,000 lx |
| 50 ph | 500,000 lx |
| 100 ph | 1,000,000 lx |
Conversion chart
1 ph10,000 lx
5 ph50,000 lx
10 ph100,000 lx
25 ph250,000 lx
50 ph500,000 lx
Worked example
1 foot-candle equals approximately 10.7639 lux.
Unit definition
Phot (ph) One phot equals 10,000 lux.
Unit history
Phot is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert ph to lux.
3. Convert the base value to lx and apply your display precision.
Understand the result before using it
Phot to Lux converts a value measured in Phot (ph) into the equivalent value in Lux (lx). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 10000 ÷ 1
Assumptions
- Phot and Lux represent the same illuminance quantity.
- The input is expressed in ph; the output is expressed in lx.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 ph = 10,000 lx. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a ph measurement in a document that expects lx.
- Compare a phot value with a value reported in lux.
- Check the ph-to-lx arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Decibel sound-pressure level is logarithmic and depends on the stated reference pressure.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Phot to Lux?
result = input × 10000 ÷ 1 Using the displayed relationship, 1 ph equals 10,000 lx.
How many Lux are in one Phot?
One Phot is 10,000 Lux. The displayed digits may be rounded.
Can I reverse the ph to lx conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts lx back to ph.
Is the Phot to Lux result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.