lux to phot | Exact Decimal + Formula

1 Lux = 0.0001 Phot

One phot equals exactly ten thousand lux. Real-world use: office and studio lighting requirements; a well-lit office is around 500 lux. This page expresses those values in phots, which is used for historic photographic and laboratory illumination specs. Type a value above for an instant answer; the exact formula and the reference table are below.

About Lux and Phot

Lux (lx)

Lux is the SI unit of illuminance — one lumen per square meter.

Where it's used: Office and studio lighting requirements; a well-lit office is around 500 lux.

Phot (ph)

A phot is one lumen per square centimeter, equal to 10,000 lux.

Where it's used: Historic photographic and laboratory illumination specs.

Illumination Converter

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Precision

Formula

ph = lx × 0.0001

To convert Lux to Phot, use the formula displayed above.

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Lux to Phot: Quick Reference Table

Lux	Phot (Decimal)	Fraction	Real-world equivalent
0.001 lx	1.0000e-7 ph	-	fractional unit measurement
0.01 lx	0.000001 ph	-	fractional unit measurement
0.1 lx	0.00001 ph	-	fractional unit measurement
0.5 lx	0.00005 ph	-	fractional unit measurement
1 lx	0.0001 ph	-	fractional unit measurement
2 lx	0.0002 ph	-	fractional unit measurement
5 lx	0.0005 ph	-	fractional unit measurement
10 lx	0.001 ph	-	fractional unit measurement
25 lx	0.0025 ph	-	fractional unit measurement
50 lx	0.005 ph	-	fractional unit measurement
100 lx	0.01 ph	-	fractional unit measurement
250 lx	0.025 ph	-	fractional unit measurement
500 lx	0.05 ph	-	fractional unit measurement
1000 lx	0.1 ph	-	fractional unit measurement

lx to ph Formula and Examples

Direct Formula ph = lx × 0.0001

Inverse Formula lx = ph × 10000

Mental Math Shortcut

Divide the value by roughly 10000 to quickly estimate the converted result.

Common Lux to Phot Calculations

5 lx = 0.0005 ph
10 lx = 0.001 ph
50 lx = 0.005 ph
100 lx = 0.01 ph
500 lx = 0.05 ph

Precision & Practical Use

For example, 10 lx = 0.001 ph — roughly fractional unit measurement.

Results are computed to up to 9 decimal places. Round to the precision of your measuring instrument — for most illumination applications, 2–3 significant figures are plenty.

How to Convert Lux to Phot

How many phots are in one lux?

One Lux (lx) equals 0.0001 Phot (ph). To convert luxes to phots, multiply the lux value by 0.0001.

How do I convert Lux to Phot?

Multiply your lux value by 0.0001 to get the result in Phot: ph = lx × 0.0001. For example, 5 lx = 0.0005 ph.

What is the formula for converting lx to ph?

The conversion formula is ph = lx × 0.0001. Use the calculator above for any value, and see the reference table below for common inputs from 0.001 to 1000.

Is there a quick mental estimate for lx to ph?