How we test
What we measure, with which instruments, and how we keep the maker's numbers apart from ours.
The short version
Beauty devices are sold with numbers: temperatures, airflow, wavelengths, microamps, joules. We explain what those numbers mean, measure them where we can, and always say whose number it is.
- Maker's figures are labelled as such ("maker's figure", "per the brand"). We repeat them only when they are published by the brand.
- Our measurements are added to a guide only after we have run them, with the instrument and conditions we used.
- Our picks are based on specs, features and availability until test results are in. We say so at the top of every guide.
What we measure
| Lab | Measurements |
|---|---|
| Hair dryers | Air temperature at 5 cm on every heat setting (thermocouple) Airflow speed at the nozzle (anemometer) Noise at arm's length (dB meter) Weight with and without the concentrator Time to dry a standard wet hair swatch |
| Multi-stylers & dryer brushes | Barrel air temperature on each setting Curl drop after 4 hours on a standard swatch Drying time from wet with the pre-styling attachment Weight and noise |
| Straighteners | Plate surface temperature along the plate (IR + thermocouple) Heat-up time to working temperature Temperature recovery after a pass of hair Passes needed to straighten a standard swatch |
| Exfoliation & dermaplaning | Suction level at each setting (vacuum gauge) Running cost per year of discs/edges Noise and battery life |
| LED face masks | Wavelength peaks (spectrometer) Irradiance at skin distance (radiometer) Coverage map of the LEDs Session length and weight |
| Microcurrent devices | Output current at each level (µA meter, test load) Waveform (oscilloscope) Battery life and charge time Gel use per session |
| IPL hair removal | Flash energy per setting (energy meter) Window temperature with and without cooling Time to treat a lower leg Accuracy of the skin-tone sensor against a reference chart |
Instruments
Type-K thermocouples and an IR thermometer for temperatures; a hot-wire anemometer for airflow; a sound-level meter for noise; a spectrometer and radiometer for LED wavelengths and irradiance; a micro-ammeter and oscilloscope with a test load for microcurrent output; and a scale for weight. Where a test needs a standard, such as a hair swatch, we use the same one for every device.
What we don't do
- We don't accept payment for inclusion, and brands don't see our guides before they are published.
- We don't make medical claims. LED, microcurrent and IPL devices are cleared for specific uses; we describe those and link to the evidence, and we tell you when to talk to a doctor first.
- We don't copy Amazon reviews or star ratings.
Corrections
If you spot a mistake, email hello@thebeautytechlab.com. We fix errors and note significant changes on the page.