Light meters, lux meters, and PAR meters

Measure light with the right unit. A lux meter measures illuminance, while the PAR meter in this section shows PPFD for the photosynthetically active range.

Choose based on the task

• Lux, lx: illuminance weighted to match human vision.
• PPFD, µmol/m²/s: photosynthetic photon flux density.
• Compare multiple points at the same height and orientation.

Can lux replace PPFD?

Conversion depends on the source spectrum. There is no universal conversion factor for all lamps. To map light distribution, measure in a grid above the plants and record the operating height.

Related measuring devices

• Measuring cups, syringes, and pipettes
• Thermo-hygrometers, thermometers, and moisture meters
• Pocket electronic scales
• CO₂ meters and stations
• Microscopes and magnifying glasses for plants

All measuring devices