PlantLux.
A unit of illuminance weighted to human visual sensitivity.
What it means for your plants
Lux readings can help compare plant locations if measured consistently. They do not directly describe all plant-usable light, and a single instant reading cannot represent a full day. Phone sensor accuracy varies.
IN PRACTICE
Measuring at leaf height near the window and on a back shelf can show a useful relative difference.
Put it into practice
Take repeatable lux readings at leaf height and use them to compare plant locations while understanding phone sensor limitations.
How to use a plant light meter without overreading the numbers