Contrary to what has been said, Kage Bunshin no jutsu splits Naruto's chakra, Bijuu chakra and SM chakra as well.
Proof:
1) Obviously, Naruto's own chakra is split. Everyone has agreed on this so far.
2) Bijuu chakra is split - This is the case because the clone is in the same rikudu mode as the real Naruto. This mode requires bijuu chakra. Also, Kurama was able to give Naruto's clone chakra to counter Edo-Madara's mokuton jutsu with rasengan barrage. This means that bijuu chakra is definitely split.
3) SM chakra is a combination of the user's chakra with natural energy. In the Pein arc, dispelling a clone redistributed the sage chakra among them. Also, to create SM clones, sage chakra must be split.
Shown.
Conclusion: There are 4 possible explanations;
1) 3 yrs of Sakura's chakra is a huge amount of chakra. This amount presumably rivals that of a Naruto clone.
2) Naruto doesn't always, necessarily distribute chakra evenly among his clones. Just because chakra is split, doesn't mean that Naruto always splits it evenly. This essentially means that the main body keeps most of the chakra.
3) Traveling to another dimension besides your own requires a huge amount of chakra.
4) Naruto has lost a considerable amount of chakra so far. He had some absorbed by Kaguya and Black Zetsu.
/Thread