Step 1: Formula for magnetic flux.
Magnetic flux \( \Phi_B \) is given by the formula:
\[
\Phi_B = B \cdot A
\]
where \( B \) is magnetic field and \( A \) is area. The magnetic field has a dimensional formula of \( [M T^{-2} A^{-1}] \).
Step 2: Conclusion.
Thus, the dimensional formula of magnetic flux is \( [M L^2 T^{-2} A^{-1}] \).