About KEV
KEV — White Balance Meter AI turns an iPhone or iPad into a colour temperature meter. Point the rear camera at a light source and it reports the colour temperature in Kelvin and the magenta/green tint in real time, so you can dial a deliberate white balance into any camera instead of trusting Auto WB.
It is a one-time purchase on the App Store. No subscription, no ads, no in-app purchases. It runs on iPhone, iPad and Apple Watch.
Who makes it
KEV is built by Satnam Singh, an independent iOS developer. The app has been on the App Store since 2020 and is currently at version 7.0.1. It has been downloaded over 92,100 times and holds 4.6 stars from 1,221 ratings - as a paid app with no free tier.
Questions, bug reports and feature requests go straight to 29satnam@gmail.com and are read by the person who wrote the code.
How the app was calibrated
The readings are not a guess derived from the camera’s own white balance estimate. KEV reads the raw colour channel ratios from the sensor before the iOS camera pipeline applies its own correction, and maps them onto colour temperature using a calibration fitted against a Sekonic C-700R-U SpectroMaster — a spectrometer that samples the spectrum across narrow wavelength slices and costs around $1,500.
That calibration is why a phone can get close to hardware at all. Under normal continuous lighting, readings typically land within 100–300K of the SpectroMaster, against roughly ±50K for the hardware itself. Most people cannot see a 200K difference in a finished image without a reference alongside it.
Where it is weaker, stated plainly:
- Very low light. Below roughly 10 lux the sensor gets noisy and readings wander.
- Flickering sources. Cheap LEDs and fluorescents pulse at mains frequency; take a median over several seconds rather than the first number.
- Spectral metrics. KEV reports Kelvin and tint. It cannot report CRI, R9, TLCI or SSI, because those need a real spectrometer. If you are vetting fixtures for purchase, that is a hardware job.
The comparison against hardware colour meters goes into where each is the right tool.
About the guides
The Learn section exists because most explanations of white balance stop at “set it to Daylight.” These guides go further: what the Kelvin scale actually measures, why tint is a separate axis, the menu path on each camera brand, and what to do when the footage is already green.
Standards applied to everything published here:
- Numbers are specific and sourced from practice. Where a figure is approximate — and most colour temperature figures are — it is given as a range, and the reasons real sources deviate from nominal values are stated.
- Limitations are named. Including the app’s own. A guide that concludes “buy our thing” for every situation is not useful, so the light meter app comparison names competing apps that are better at exposure metering, which KEV does not do at all.
- Every guide carries a last-updated date. Camera menu paths change between firmware versions.
If you find something wrong, email it and it gets corrected.
Privacy
KEV analyses camera frames on-device. Nothing is uploaded, and no personal data is collected. Full detail in the privacy policy.