Dr.meter LX1330B

The LX1330B has been sold under many labels for years, and that is its advantage: people have measured it. In a 2018 Budget Light Forum comparison against a MobiLux Class A meter, an unbranded LX-1330B read a 4,000 K LED almost exactly, read another LED 8% low and read a 6,500 K LED 20% high.

The tester later summarized it as a 3.2% average calibration offset with 8.3% spread across sources. That is good for the money, but it means you should treat readings under LEDs as approximate.

The reason is in the manual. Dr.meter calibrates the meter to a 2,856 K incandescent lamp. Under incandescent or halogen light it should be close to spec. Under LEDs, whose spectra differ, the error depends on the LED.

For a SAD lamp check, that error matters less than distance. In a study of light therapy devices, one box measured about 12,000 lux at 20 inches and about 7,000 at 28 inches (Oldham 2019). Measure at eye height with the probe facing the lamp.

Two quirks to know. Ranges are manual, so you must press the range button to reach 20,000 or 200,000 lux. And the display only shows up to 1999, so on the 20,000 lux range a reading of 1000 means 10,000 lux.

Dr.meter’s product page lists accuracy as ±3% ±10 digits, while its PDF manual says ±(4% + 10 digits) below 20,000 lux. The table above uses the more conservative manual figure.

If you want app logging and do not mind a built-in sensor, the UNI-T UT383BT costs about $10 less. If you want cosine correction and a firmer spec, the Extech LT300 is the step up.