Free reference tools for working with motion picture film: calculate footage and running time, estimate the storage a scan will need, identify an unknown gauge, check reel capacity, and date a reel by its Kodak edge code.
Not sure what you have? Measure the width of the film and match the perforations. The strips below are drawn to scale relative to one another.
| Gauge | Perforations | About |
|---|---|---|
| Regular 8mm | One edge, larger holes at the frame lines | Narrow film with sprocket holes down one side and small, nearly square frames. Kodak introduced it in 1932 as an affordable home format: 16mm stock was exposed down one half, flipped and run through again, then slit down the middle to yield two 8mm strips. It dominated home movies from the 1930s into the 1960s and usually turns up on 3-inch (50 ft) reels. |
| Super 8 | One edge, smaller holes centered on each frame | The same 8mm width as Regular 8, but with much smaller perforations that freed up room for a frame about 50 percent larger. Kodak launched it in 1965 in an easy-load plastic cartridge, which is often the giveaway. It became the standard home-movie and student format through the 1970s, and many later cartridges carried a magnetic sound stripe. |
| 16mm | One edge (sound) or both edges (silent) | Twice the width of 8mm, introduced by Kodak in 1923 as a safer, cheaper alternative to 35mm. Silent 16mm has perforations on both edges; a sound print gives up one row for an optical or magnetic track, so perforations on only one edge signal sound. It was long the workhorse of documentary, newsreel, educational, and industrial filmmaking. |
| Super 16 | One edge only | Standard 16mm stock exposed with a single row of perforations, letting the frame extend into the space the second row would use for a wider image of roughly 1.66. It is a camera origination format rather than a projection one, meant to be blown up to 35mm or finished for widescreen. A single perf row plus a frame reaching almost to the far edge is the tell. |
| 35mm | Both edges, four holes per frame | The theatrical standard since the birth of cinema, with perforations down both edges, usually four per frame. It is exactly the same width as a 35mm still-photography negative, because motion-picture film came first and the still format borrowed the stock. Its large frame and a century of infrastructure make it the benchmark other gauges are measured against. |
Convert between footage, running time, and frame count for 8mm, Super 8mm, 16mm, 35mm, and 65mm at any frame rate. Pick a film format and frame rate, then type a number into any one of the three boxes below (footage, running time, or frames) and the other two update automatically to show the matching values.
Estimate the storage a film scan will require. Pick a resolution, delivery format, frame rate, and length, and see the total file size, the data rate, and the size per hour of footage.
Convert between feet+frames, timecode (HH:MM:SS:FF), and a total frame count. Feet+frames follows the film gauge (35mm is 16 frames per foot, 16mm is 40); timecode follows the frame rate. Pick a format and frame rate, then type into any one box and the other two update automatically.
For most of the twentieth century, Eastman Kodak printed a small symbol code along the edge of its motion-picture film, outside the perforations, to mark the year the stock was made. The symbols differ by the plant that coated the film, so choose the plant first. Then read the symbols left to right and pick them below, filling only as many as your film shows. This is the year the film was manufactured, not necessarily when it was shot or processed.
Pick the symbols you see, in order.
Alongside the date symbols, Kodak printed the word SAFETY on acetate stock, and a single dot above the word identified the factory that coated the film. The dot sits between two letters, not over one, and its position is what matters: read which pair of letters it falls between. Kodak began marking the Rochester plant around 1927 and the overseas plants in Canada and England around 1936.
The footage and running time a full reel holds, by gauge and reel size. Super 8 is shown at 18 fps and Regular 8 at 16 fps, their silent standards; 16mm and 35mm at 24 fps. Reel sizes are nominal outer diameters.
| Gauge | Reel size | Approx. length | Running time |
|---|---|---|---|
| Super 8 | 3 in | 50 ft | about 3.5 min |
| Super 8 | 5 in | 200 ft | about 13 min |
| Super 8 | 7 in | 400 ft | about 27 min |
| Regular 8 | 3 in | 50 ft | about 4 min |
| Regular 8 | 5 in | 200 ft | about 17 min |
| Regular 8 | 7 in | 400 ft | about 33 min |
| 16mm | 3.625 in | 100 ft | about 2.75 min |
| 16mm | 5 in | 200 ft | about 5.5 min |
| 16mm | 7 in | 400 ft | about 11 min |
| 16mm | 10.5 in | 800 ft | about 22 min |
| 16mm | 11.5 in | 1000 ft | about 28 min |
| 16mm | 12.25 in | 1200 ft | about 33 min |
| 16mm | 13.75 in | 1600 ft | about 44 min |
| 16mm | 14.5 in | 1800 ft | about 50 min |
| 16mm | 15 in | 2000 ft | about 56 min |
| 35mm | ~10.5 in | 1000 ft | about 11 min |
| 35mm | 15 in | 2000 ft | about 22 min |
Need it exact? Use the Film footage calculator above to convert any footage, running time, or frame count for your gauge and frame rate.
The aspect ratios you are most likely to meet in a film collection, from silent Academy to modern anamorphic scope.
| Ratio | Name | About | Shape |
|---|---|---|---|
| 1.19:1 | Movietone | One of the first sound-on-film formats, introduced by Fox in the late 1920s. Fitting an optical soundtrack beside the picture narrowed the frame to a nearly square shape, a look that lasted only until the Academy ratio standardized the sound-era frame. | |
| 1.33:1 | Silent / full aperture (4:3) | The classic 4:3 rectangle. It fills the full 35mm camera aperture of the silent era and is the native shape of Regular 8, Super 8, and 16mm film, as well as pre-widescreen television. | |
| 1.37:1 | Academy | Standardized by the Academy of Motion Picture Arts and Sciences in 1932. To make room for an optical soundtrack running alongside the picture, the image area was reduced, and the frame was then reshaped into a balanced rectangle. It stayed the theatrical norm until widescreen arrived in the 1950s. | |
| 1.43:1 | IMAX | The largest common film format. 65/70mm stock runs sideways through the camera rather than vertically, each frame spanning 15 perforations, producing a negative roughly ten times the area of a standard 35mm frame. | |
| 1.66:1 | European widescreen | A modest widescreen that became a common projection standard across Europe from the 1950s onward. It is also the native shape of Super 16, often used to originate material for wider finishing. | |
| 1.78:1 | 16:9 | The shape of HD and modern digital video and displays. It sits between 1.66 and 1.85, chosen as a compromise widescreen for presenting both older and theatrical material on television. | |
| 1.85:1 | US widescreen (flat) | The standard American "flat" widescreen since the mid-1950s. It is created by masking the top and bottom of a full 35mm frame in projection, rather than with an anamorphic lens. | |
| 2.20:1 | 70mm | The presentation ratio of traditional 5-perf 70mm roadshow films. The wide frame and large negative made it the premium large-format experience of its era. | |
| 2.35:1 | CinemaScope / early scope | The original anamorphic widescreen, horizontally squeezed onto 35mm by a special lens and unsqueezed in projection. It ran from CinemaScope's 1953 debut until the anamorphic standard was slightly revised in 1970. | |
| 2.39:1 | Modern anamorphic (scope) | The current anamorphic "scope" standard, a 1970 refinement of the earlier 2.35 that made frame-line splices less visible. It remains the widest ratio in everyday theatrical use. |
