The association of starspots with magnetic fields leads to an expectation that quantities which correlate with magnetic field strength may also correlate with spot coverage .
Since younger stars spin faster and are more magnetically active , assessing whether spot coverage correlates with shorter rotation periods and stellar youth tests these principles .
Here we analyze the spot covering fraction versus stellar age for M , G , K , and F type stars based on previously determined variability and rotation periods of over 30,000 Kepler main-sequence stars .
We determine the correlation between age and variability using single and dual power law best fits .
We find that spot coverage does indeed decrease with age .
Only when the data are binned in an effort to remove the effects of activity cycles of individual stars , do statistically significant power law fits emerge for each stellar type .
Then we find that the spot covering fraction scales with the x-ray to bolometric ratio to the power \lambda with 0.21 \pm 0.03 < \lambda < 0.35 \pm 0.12 for G stars of rotation period below 15 days and for the full range of F and M stars .
For K type stars , we find two branches of \lambda separated by variability bins , with the lower branch showing nearly constant spot coverage and the upper branch \lambda \sim 0.36 \pm 0.04 .
G type stars with periods longer than 15 days exhibit a transition to steeper power law of \lambda \sim 3.4 \pm 1.3 .
The potential connection to previous rotation-age measurements suggesting a magnetic breaking transition at the solar age , corresponding to period of 24.5 is also of interest .