This page opens on 4100 K, the cool white of office lighting, and has five more, from warm 2700 K to 6500 K daylight. Open it on a tablet, a phone or a second monitor, press Full screen, and stand it in front of you while the call runs on your main screen. Space steps from warm to cool, and the swatches pick one directly.
Match the white to the room
Light bulbs are sold by color temperature, in kelvin (K), and the number is printed on the box. ENERGY STAR groups them as warm white at 2700 to 3000 K, the yellowish glow of an old incandescent bulb, bright or cool white at 3500 to 4100 K, and daylight at 5000 to 6500 K. The US Department of Energy’s buying guide for federal buildings suggests 2700 K for homes and 4100 K for offices and classrooms.
Choose the swatch nearest to the light already on your face. If the screen and the ceiling light differ, one side of your face comes out orange and the other bluish, and the camera’s automatic white balance can only correct one of them. By day, with a window as your main light, use 5000 K or 6500 K.
Warmer whites give less light
A screen makes a warm white by holding back blue and some green, so every step warmer costs light. On a screen set to sRGB, 2700 K gives about half the light of full white and 4100 K about 72%; the table below lists every swatch. If your face is still too dark, move the screen closer or pick a cooler white before going warmer. The page can’t raise the screen’s own brightness, so turn that to maximum in the device’s settings.
Where to put the screen
Stand it just behind or beside your camera, facing you, with its center around eye level: light from below casts shadows upward across the face. A tablet or phone is a small light, so it works best within an arm’s length. Avoid sitting with a bright window behind you, which leaves your face in shadow whatever the screen does. Before you join, look at yourself in the webcam test to judge the light.
How the swatches were worked out
Each swatch is the color of an ideal glowing body (a blackbody) at that temperature: Planck’s law weighted by the CIE 1931 standard observer’s color matching functions, as published by the Colour & Vision Research Laboratory, then converted to screen color with the sRGB matrix in the W3C’s CSS Color 4 specification and scaled until its strongest channel is full. The 6500 K swatch is the screen’s own white, #ffffff: sRGB uses the CIE’s D65 daylight as its white, which the CIE gives a correlated color temperature of about 6,500 K.
The match holds only while the screen shows colors as they are. On an iPhone or iPad, Night Shift moves the display toward the warm end and True Tone adjusts it to the light around you, according to Apple, so turn both off while you use the page as a light.
On a Mac, no second screen needed
Macs with Apple silicon running macOS Tahoe 26.2 or later have Edge Light. During a video call, choose it from the Video menu in the menu bar and the edges of the screen glow like a ring light, with sliders for brightness (the width of the glow) and color temperature. Apple says it works best in low light, such as indoors at night.
For other colors go back to the black screen. For plain bright white that ignores a resting hand, use the tracing light box; to check a new OLED screen, run the OLED test.
The 6 colors on this page
| Color | Code | Light |
|---|---|---|
| 2700 K | #ffad59 | 52% |
| 3000 K | #ffb86d | 57% |
| 3500 K | #ffc78b | 64% |
| 4100 K | #ffd5aa | 72% |
| 5000 K | #ffe6d0 | 82% |
| 6500 K | #ffffff | 100% |