Blue Light Calculator
Pick your device and night filter to see the colour temperature your screen runs at in the evening.
Display colour temperature
6500K
Your MacBook Pro with no night filter runs at 6500 K.
About this setting
With no night filter, your screen stays at its plain 6500 K white point. Night Shift, f.lux and Sundown can each warm it in the evening.
Your Setup vs Sundown
Your current setup
Colour temperature
6500K
With Sundown at its warmest
Colour temperature
500K
Sundown's warmth ladder runs from 6500 K down to 500 K in 100 K steps, so you can stop anywhere along it.
This tool shows colour temperature only. For what the studies do and do not show, read screen flicker and eye strain and the science.
How this blue light calculator works
Colour temperature
Each night filter runs the display at a colour temperature, measured in kelvin. A plain screen sits at 6500 K. Lower numbers are warmer, more orange-red light. The swatch is an approximate preview of that white point.
The settings
Night Shift and f.lux both warm the display, each down to its own lowest setting. Sundown's warmth control is a Kelvin ladder that runs from 6500 K down to 500 K in 100 K steps. At 500 K, its lowest setting, Sundown shows its warmest light.
Reading the result
Each setting at its warmest
| Setting | Colour temperature | How the screen looks |
|---|---|---|
| No filter | 6500 K | Plain white, the colour of daylight |
| Night Shift (More Warm) | about 2700 K | A warm white, like an indoor bulb |
| f.lux (Ember, its warmest preset) | 1200 K | Deep orange |
| Sundown (lowest step) | 500 K | Deep red |
Why the swatch may not match your screen
The swatch is drawn by your browser on a screen that is already running at its own white point, so it is a preview and not a measurement. If Night Shift, True Tone or another filter is on while you read this, every swatch shifts with it. Turn them off for a moment if you want the cleanest comparison.
Warming the screen through the evening
Most people do not jump straight to the warmest setting. A common pattern is a warm white after sunset, a deeper orange later on, and deep red in the last hour before bed, because a sudden change is harder to get used to than a gradual one. Sundown can step down on a schedule you set, so the screen gets there without you touching it. Our evening routine by kelvin walks through one way to set it up.
Questions people ask
Does Dark Mode change the colour temperature?
No. Dark Mode makes the interface darker, so less light of every colour reaches you, but the white that is left on screen is still 6500 K. Warming the screen is a separate setting.
How warm can Night Shift go?
Night Shift tops out at about 2700 K with its slider at More Warm. Apple does not publish the figure, so treat it as an approximate value.
Does the device I pick change the number?
The kelvin comes from the filter you pick. The device changes how the result is described, because panels, brightness and calibration differ from one screen to the next.
Can I share a result or put the calculator on my site?
Yes. Share Results copies a link that opens the calculator on the same device and filter, and the embed code below adds the calculator to any page.
Further reading
- Color temperature explained: what kelvin means on a Mac screen.
- Sundown vs Night Shift: the two compared setting by setting.
- Sundown vs f.lux: how far each one warms the screen.
- Dark Mode vs Night Shift vs True Tone: what each built-in setting changes.
Embed this calculator
You can add this calculator to your own site. Copy the code below and paste it into your page.
<iframe title="Blue light calculator" src="https://trysundown.com/embed/blue-light-calculator" width="100%" height="1400" style="border:0;max-width:760px" loading="lazy"></iframe>
<p>Blue light calculator by <a href="https://trysundown.com/tools/blue-light-calculator">Sundown</a></p>