5500K is photographer shorthand for neutral daylight. It’s the colour temperature of midday sun on a clear day, and the value most flashes, LED panels and HMI bulbs are tuned to. When you see “5500K” on a strobe box, that’s why.
But to actually use that information, you need the Kelvin scale.
The Kelvin scale in 60 seconds
The Kelvin scale measures colour temperature - the colour of light a black object would emit when heated. Lower temperatures glow red-orange (think a campfire); higher temperatures glow blue-white (think a star).
For photographers and filmmakers, lower Kelvin = warmer light, higher Kelvin = cooler light.
Common Kelvin values
| Kelvin | Light source | Looks like |
|---|---|---|
| 1800K | Candle flame, gas lamp | Deep amber |
| 2500K | Sunrise / sunset | Golden orange |
| 2800K | Soft white incandescent bulb | Warm yellow |
| 3200K | Standard tungsten / halogen | Yellow-orange |
| 4000K | Warm fluorescent | Pale yellow |
| 4500K | Cool fluorescent / moonlight | Near-neutral |
| 5000K | Horizon daylight | Slightly warm white |
| 5500K | Midday sun, camera flash, daylight LED | Neutral white |
| 6000K | Overcast sky | Slightly blue |
| 6500K | Cloudy daylight, “daylight” monitors | Cool blue |
| 7500K | Open shade | Blue |
| 10000K+ | Deep blue sky (north light) | Strong blue |
Why 5500K is the reference
Camera sensors and film stock are designed around two anchor points: 3200K (tungsten) and 5500K (daylight). Almost everything else is a deviation from one of those two.
- A daylight-balanced light source = 5500K.
- A tungsten-balanced light source = 3200K.
- A bi-colour LED panel = adjustable between 2700K and 6500K.
When you set a camera’s white balance to “Daylight,” you’re telling it to assume the light is 5500K. If you light the scene with HMI or daylight LEDs (both 5500K), white objects render white. If you light with tungsten at 3200K but leave WB on Daylight, white objects render orange on the sensor.
How to find the actual Kelvin of a scene
You don’t have to guess. Point a phone-based meter at the scene and read the number.
- Install KEV - White Balance Meter AI on your iPhone or iPad.
- Open the app, aim the rear camera at the light source or the subject.
- The Kelvin value (plus magenta/green tint) updates in real time.
Then dial that exact Kelvin into your camera’s custom white balance.
Full step-by-step → How to measure color temperature with your iPhone
Tips for using the Kelvin scale on set
- Bi-colour LEDs: match your key light to the practicals. If the room’s tungsten bulbs read 2900K, set your LED to 2900K, not 3200K.
- Magic hour: Kelvin shifts ~200K every five minutes near sunset. Re-meter often.
- Mixed sources: meter each one. Then either gel them to match, or pick a Kelvin between them as a compromise WB.
- Shooting log/RAW: you can fix Kelvin in post, but you cannot fix it if AWB drifted shot-to-shot. Lock it manually.