How fast could an aneurysm grow?

Depends: On type and location of aneurysm. Can you add specifics?

Varies: Usually millimeters per year. If more then surgery or intervention needed if other size and risk factors suitable.

Varies: Really depends on location and size. Typically and aortic aneurysm can grow about 1/3 cm per year but that is highly variable. Larger aneurysms grow faster than smaller aneurysms