Comparison
Sundown vs f.lux: Which Mac Blue Light Filter Is Better?
One stops at 1200K. The other reaches 500K. Here’s the full comparison.
Feature
Sundown
f.lux
Filtering depth
500K500K
1200K
Last updated
September 2026September 2026
May 2023
Flicker-Free Mode
Gamma dimming, backlight steadyGamma dimming, backlight steady
Brightness control
F1/F2 keysF1/F2 keys
Scheduling
CustomCustom
By location or wake time
Anti-dithering
Apple SiliconApple Silicon
Price
$4.99/mo (7-day free trial)$4.99/mo (7-day free trial)
Free
f.lux stops at 1200K (its warmest preset, “Ember”). Sundown reaches 500K.
f.lux was groundbreaking in 2009. f.lux still ships — its Windows build is dated 8 April 2026. The Mac build hasn’t changed since 17 May 2023. Sundown is native macOS, built for Apple Silicon, dims through the gamma table with the backlight steady, and reaches a 500K deep red.
~58%
More nocturnal melatonin with blue-blocking glasses
~24 min
Longer sleep with the same glasses
Melatonin and sleep-duration figures: Ostrin et al. 2017 (PMID 28656675): healthy adults wore short-wavelength-blocking glasses before bed for two weeks. A study of glasses, not of Sundown.
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