Calculating for respooling

I cannot for the life of me figure out a proper equation for spooling fresh tape onto a cart reel. 3.75ips equates to 225” per minute, for for a 60 minute cart, I’d need roughly 3375” or just over 280 feet. Am I figuring that correctly? It seems unimaginable that it’d be that much, but there’s a reason I flunked out of engineering school. Anyone done this? I think I found a source for new graphite-backed tape stock, but I want to be sure before I order a reel. Thanks!