Understanding HDTV Aspect Ratio

This question is frequently asked, and it’s referring to the black bars you see on top and bottom of movies on your widescreen TV. Well here’s a good guide on just why they exist and how it actually is a good thing as it lets you see the whole picture.

Not that big of a deal, right? Barely noticeable bars. We’ve had movies even longer than TV, and there has never been a “standard” aspect ratio. The common ones are 1.85:1, 2.35:1 and 2:40:1, though a few films were even wider, 2.55:1 or even 2.76:1. Most big Hollywood movies are 2.35:1 (usually pre-1970) or 2.40:1 (after 1970) though there are exceptions.


  • The article neglected to

    The article neglected to mention that the 16:9 (1.78:1) ratio actually has very sound reasoning behind it. It is the geometric mean between 1.33:1, 1.85:1 and 2.35:1. The idea was to compromise on a format that could be all-purpose. The result is a size just about perfect for 1.85:1 and with equal amounts of black bar area when watching 1.33:1 or 2.35:1. Here are some mathematical examples to illustrate the point.