Luminous flux is the visible light output used in lumen-based calculations.
Luminous flux is visible light output, expressed in lumens. It is the quantity used before area, spacing and delivery assumptions turn output into illuminance.
Technical meaning
Luminous flux describes the amount of visible light output from a source, lamp or luminaire.
The value used in an estimate should match the output basis for the installed fitting rather than mixing bare-lamp and complete-luminaire figures.
Calculation use
Flux is converted into illuminance when it is distributed across an assessed area with UF and MF assumptions.
Fixture-count estimates divide the required flux allowance by the output from one fitting, then round up to a whole count.
Not the same as
Luminous flux is not illuminance. The same lumens can produce different lux values in different areas or distributions.
Luminous flux is not wattage. Input power belongs to load and energy calculations.
Australian context
Australian lighting schedules should keep luminous flux, connected load, colour temperature, CRI, IP rating and driver information as separate fields.
Examples
Example
Value
Planning note
Single downlight
900 lm
Useful for fixture count after the target lumen allowance is known.
Luminaire group
12 x 900 lm
Installed output still needs delivery and task-plane checks.