Milliwatts to photons per second
Type a value in mW to get it in photons/s instantly.
1.279×10¹⁵photons/s
That's 1,278,665,606× as bright as a sensitive detector, while a laser pointer is 2.3× more. That is about 0.002123 µmol of photons a second.
Convert the other way: photons/s to mW
What it means
How many photons?
This counts photons arriving, not photons detected. A detector’s quantum efficiency decides how many of them are actually recorded.
The math
How to convert mW to photons/s
Each photon carries E = hc ÷ λ, so photons per second = watts × λ(nm) ÷ 1.986 × 10⁻¹⁶. The figures below use the wavelength selected above.
Example: 1 mW = 1.279×10¹⁵ photons/s.
The table below is for Ultraviolet, 254 nm.
Every unit
Your flux in every unit
Tables
mW to photons/s conversion table
| mW | photons/s |
|---|---|
| 1,000 mW | 1.279×10¹⁸ photons/s |
| 1,000,000 mW | 1.279×10²¹ photons/s |
| 1×10⁹ mW | 1.279×10²⁴ photons/s |
| 1×10¹² mW | 1.279×10²⁷ photons/s |
| 1×10¹⁵ mW | 1.279×10³⁰ photons/s |
| 1×10¹⁶ mW | 1.279×10³¹ photons/s |
| 1×10¹⁷ mW | 1.279×10³² photons/s |
| 1×10¹⁸ mW | 1.279×10³³ photons/s |
| 1×10²⁰ mW | 1.279×10³⁵ photons/s |
photons/s to mW conversion table
| photons/s | mW |
|---|---|
| 1,000 photons/s | 7.821×10⁻¹³ mW |
| 1,000,000 photons/s | 7.821×10⁻¹⁰ mW |
| 1×10⁹ photons/s | 7.821×10⁻⁷ mW |
| 1×10¹² photons/s | 0.000782065 mW |
| 1×10¹⁵ photons/s | 0.782065 mW |
| 1×10¹⁶ photons/s | 7.82065 mW |
| 1×10¹⁷ photons/s | 78.2065 mW |
| 1×10¹⁸ photons/s | 782.065 mW |
| 1×10²⁰ photons/s | 78,206.5 mW |
Quick answers
Quick answers
- How many photons/s is 1 mW?
- 1 mW is 1.279×10¹⁵ photons/s.
- How many photons/s is 10 mW?
- 10 mW is 1.279×10¹⁶ photons/s.
The units
About these units
Milliwatts (mW)
The scale of laser pointers and laboratory diodes.
Photons per second (photons/s)
The raw count of photons arriving each second.
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