It's difficult to give an exact diameter for the Milky Way in miles because its edges are not clearly defined. However, here's what we know:

* Estimated Diameter: The Milky Way is estimated to be about 100,000 light-years across.

* Converting to Miles: One light-year is approximately 5.88 trillion miles.

* Calculation: 100,000 light-years * 5.88 trillion miles/light-year = 588 quadrillion miles

Therefore, the Milky Way is roughly 588 quadrillion miles in diameter.