Lux to phots
Type a value in lux to see it in phots straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the lux box.
- Read the result in phots as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
ph = lx × 0.0001
Multiply the value in lux by 0.0001 to get phots.
Example
To convert 25 lx to phots: 25 × 0.0001 = 0.0025 ph.
Conversion table
| Lux (lx) | Phots (ph) |
|---|---|
| 1 | 0.0001 |
| 2 | 0.0002 |
| 3 | 0.0003 |
| 5 | 0.0005 |
| 10 | 0.001 |
| 20 | 0.002 |
| 25 | 0.0025 |
| 50 | 0.005 |
| 100 | 0.01 |
| 250 | 0.025 |
| 500 | 0.05 |
| 1,000 | 0.1 |
About the units
- Lux
- The SI unit of illuminance, equal to one lumen spread over one square meter.
- Phot
- The CGS unit of illuminance, one lumen per square centimeter, exactly 10000 lux.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many phots are in one lux?
1 lx = 0.0001 ph exactly.
How do I convert lux to phots?
Use ph = lx × 0.0001. For example, 25 lx = 0.0025 ph.
How many lux are in one phot?
1 ph = 10,000 lx.
What is the difference between lux and lumens?
Lumens are the total light a lamp emits, while lux is how much of it lands on each square meter. A 1000 lumen lamp spread over 10 square meters gives 100 lux.
Why is a foot-candle about 10.764 lux?
A square foot is exactly 0.09290304 square meters, so one lumen per square foot equals 1 / 0.09290304 lumens per square meter.