Google is your friend. Google "Frontal RCS XXX" (where "XXX" is the designation, such as F-22, of the aircraft of interest) and you will get many hits.
For the Google impaired, here are two links:
According to November 2005 reports, the US Air Force states that the F-22 has the lowest RCS of any manned aircraft in the USAF inventory, with a frontal RCS of 0.0001~0.0002 m2, marble sized in frontal aspect. According to these reports, the F-35 is said to have an RCS equal to a metal golf ball, about 0.0015m2, which is about 5 to 10 times greater than the minimal frontal RCS of F/A-22. The F-35 has a lower RCS than the F-117 and is comparable to the B-2, which was half that of the older F-117. Other reports claim that the F-35 is said to have an smaller RCS headon than the F-22, but from all other angles the F-35 RCS is greater. By comparison, the RCS of the Mig-29 is about 5m2.
F-35 Joint Strike Fighter Lightning II
It is claimed that the Super Hornet employs the most extensive radar cross section reduction measures of any contemporary fighter, other than the F-22 and F-35. While the F/A-18E/F is not a stealth fighter like the F-22, it will have a frontal radar cross-section an order of magnitude smaller than prior generation fighters. Additional changes for reducing RCS can be installed on an as-needed basis.
(one order magnitude less than 5m2 is .5m2, about the same as T-50)
https://en.wikipedia.org/wiki/Boeing...ction_measures
Once again, you can trust the public sources of this data, or not. But the data most certainly is available and I did not "make it up" as was claimed.