Fluence converter
Convert energy per unit area between mJ/cm² and J/m², the units of laser pulses and UV disinfection doses.
That's about the same as a UV water disinfection dose. A 1 mW/cm² source would need about 40 seconds to deliver it.
What it means
How big a dose is that?
Fluence is energy per area. Irradiance — watts per square meter — is the rate; multiply by the exposure time to get fluence.
Every unit
Your dose in every unit
Learn
Three things worth knowing
-
1 mJ/cm² = 10 J/m²
A square meter is ten thousand square centimeters, and a millijoule is a thousandth of a joule, so the two factors leave a clean ten.
-
Dose, not power
What matters biologically and industrially is the total energy delivered, not how fast. A weak lamp for a long time does the same job as a strong one briefly.
-
Fluence is not irradiance
mW/cm² is a rate; mJ/cm² is a total. One second at 1 mW/cm² gives 1 mJ/cm², so the numbers coincide only for one second.
Shortcuts
Popular dose conversions
Background
About fluence
Fluence is how much energy lands on each patch of surface, and it decides what actually happens: at 1 J/cm² a laser marks metal, at 5 it starts removing it.
UV disinfection works the same way: 40 mJ/cm² at 254 nm is the standard dose for drinking water, whatever lamp delivers it.