It depends on the manufacture. I just got some Mcculloch bulbs and their 8000k bulb is claiming to be 3000 lumens while their 4700k bulb claims to be 3700 lumens. To give you a comparison, 4300k philips is around 3000 lumens too. I have no clue if the numbers Mcculloch numbers are exaggerated, but that's just what they gave me