Knowing the different 16mm and 8mm reel sizes can help you estimate film length without measuring film by hand. Most home movie to DVD services charge by the foot or by the diameter of the film reel itself, so let's figure out how much film you have.

Different Film Reel Sizes

A reel is just a plastic cylinder that stores a segment of film. It includes the center rod that the film gets wrapped around, and flat circular caps mounted on each end of the rod to hold the film in place.

Here are a few tips for measuring film reel size:

  • Check the reel's diameter. Use a ruler to measure the reel at its widest point. How many inches across is it?
  • Check the reel for numbers. Some reels have markings to help you calculate film length if the reel isn't full.
  • Check the rolled-up film's diameter. If a reel does not have markings and is not full, peek through the holes in the reel to measure the diameter of the film itself.

Measuring Film Length in Footage and Playback Time

Most 16mm and 8mm film reels are 3, 5, or 7 inches across. Assuming they're full, larger reels naturally hold more film -- not just in feet, but in minutes, too.

After measuring film reel diameter, use this guide to estimate how much footage you have. The run times are based on a standard playback speed of 18 frames per second (fps).

Reel DiameterFilm LengthRun Time (18 fps)
3 inches50 feet3-4 minutes
5 inches200 feet14-16 minutes
7 inches400 feet28-32 minutes
These numbers come from a piece on our parent company's site. Visit their blog for a full table of film reel sizes, and check out their one-minute video on measuring film.

Converting 8mm to DVD? Measure Your Film First

Again, the pricing of home movie transfers is normally based on how much footage you have. Measuring film reel size is a smart way to predict how much your project will cost -- and how many minutes of digital video you'll get to enjoy when it's done!