This one is tricky. Since Galactus can vary greatly If he has consumed 4 or 5 planets in a row he can be near 200 and he can be as low as 50. Surfer is a solid 12 to 15 depending on his mood/writer.
I always assumed Galactus could absorb only so much energy reaching a limit he couldn't go beyond and any residual/additional energy was transferred into the reserves of his spaceship.
Posted with Google Chrome 63.0.3239.132 on Windows 10