How big can film be enlarged?

When we want to enlarge a negative, the first question is: How large should we enlarge it?

This is a question that is difficult to answer briefly, because it really depends on a lot of factors like the quality of your lens or your viewing distance.

Instead of begin a long speech, let's first look at an example.

This is a 120 Fuji Pro 400H film enlarged to A3 size. (420mm x 420mm)

Taken with Zeiss Biogon 38mm F4.5, the legendary Hasselblad SWC/M, easily pushed to 7x film size. You won't see any blurriness or grain at normal viewing distance. Even after magnifying with a macro lens, it still showing great detail.

So when it comes to “enlarge”, it's all about what kind of experience are you looking for?

Don't think of it as a digital photo. Don't bother how much the ppi is. Try to think how big of a photo would you like to hold in your hand? Or how big of a photo do you want to hang on the wall?

Once you have some idea about the two questions above, feel free to go ahead and make it bigger. Don't hesitate or be afraid of the outcome, you can always trust your film.