Aspect ratio calculator
Pick a film's shape and your screen's size, and see exactly how thick the black bars will be: top and bottom for wide films, left and right for narrow ones.
Letterbox: two bars, top and bottom
- Each bar
- 276 px and 277 px
- Picture
- 3840 × 1607 px
- Screen used
- 74.4%
| Film | Bars | Each bar | Screen used |
|---|---|---|---|
| 1.33:1 (4:3) | pillarbox | 480 px | 75% |
| 1.37:1 Academy | pillarbox | 435 px | 77% |
| 1.66:1 | pillarbox | 127 px | 93% |
| 1.85:1 | letterbox | 42 px | 96% |
| 2.00:1 | letterbox | 120 px | 89% |
| 2.20:1 | letterbox | 207/208 px | 81% |
| 2.39:1 'scope' | letterbox | 276/277 px | 74% |
| 2.76:1 | letterbox | 384/385 px | 64% |
How it works
An aspect ratio is a picture's width divided by its height. To show a whole film without cropping or stretching it, the player scales it until it touches two edges of the screen. A film wider than the screen keeps the full width and leaves bars above and below (letterbox); a narrower one keeps the full height and leaves bars at the sides (pillarbox).
For a letterbox, the picture height is the screen width divided by the film's ratio, and each bar is half of what is left. A 2.39:1 film on a 3840 × 2160 screen is 3840 ÷ 2.39 = 1607 pixels tall, leaving 553 pixels: bars of 276 and 277. For a pillarbox, the picture width is the screen height times the ratio.
In pixels the picture is rounded to whole pixels, so the two bars can differ by one. In centimetres or inches the answer is exact. Enter a projection screen's size to see how much of it a film will use.
Common film ratios
- 1.33:1 (4:3): The original 35 mm silent-film frame, in use since the first motion-picture cameras; known on TV and video as 4:3.
- 1.37:1 Academy: The Academy ratio, officially adopted by the Academy of Motion Picture Arts and Sciences in 1932 and used for sound films until 1953.
- 1.66:1: An early 35 mm widescreen ratio first introduced by Paramount Pictures, later a widescreen standard in parts of Europe.
- 1.85:1: A 35 mm widescreen ratio introduced by Universal Pictures in May 1953.
- 2.00:1: First used in the 1950s for RKO's Superscope; since 1998 cinematographer Vittorio Storaro has championed it as 'Univisium'.
- 2.20:1: Developed for the 70 mm Todd-AO process in the 1950s.
- 2.39:1 'scope': Anamorphic widescreen: standardised at 2.35:1, then changed to 2.39:1 by a 1970 SMPTE update (PH22.106-1971) to make splices less noticeable.
- 2.76:1: Ultra Panavision 70: 65 mm film with a 1.25× anamorphic squeeze, used on a handful of films between 1957 and 1966.
Sources
- The history of each ratio above: Aspect ratio (image), Wikipedia, sections on film and on previous and currently used aspect ratios.
- Centimetre and inch conversions (1 in = 2.54 cm exactly): NIST Guide to the SI (SP 811), Appendix B.9.
Questions
Why does my widescreen TV still show black bars?
Because many films are wider than 16:9. A 2.39:1 film on a 16:9 TV uses about three-quarters of the screen's height. The bars are the price of seeing the whole frame the film-makers composed.
Is 2.35:1 the same as 2.39:1?
Nearly. Anamorphic "scope" was standardised at 2.35:1 and changed to 2.39:1 in 1970; people still use both names, and 2.40:1 too. On a 3840 × 2160 screen a 2.35:1 picture is 27 pixels taller, so each bar is about 14 pixels thinner. Type 2.35 or 2.40 under "Other ratio" to compare.
What screen shape should I buy for a projector?
A 16:9 screen suits TV, sport and most streaming. A 2.39:1 screen shows scope films edge to edge but leaves 16:9 pictures with bars at the sides, unless your projector can zoom them to fill the screen's height. Compare both with the table above.