Exact Progress Bar

In TV and movies, all computer operations take an exact, known amount of time to perform, and all progress bars move smoothly at a constant rate. This will always be 100% accurate. Generally, in Real Life, it's more complicated. Just try copying a large folder in Windows and see for yourself.

In real life, some jobs are predictable and some are not, and this is always highly dependent on actual implementation details that are beyond this article.

See also Beeping Computers and Magic Countdown.

Anime and Manga

 * Averted in Lucky Star, where Konata is increasingly annoyed by the realistically fluctuating progress bar on her PC.
 * Digimon Tamers, which normally takes a tremendous amount of liberties with how computers and networks work, averts this at least once. Progress on a set of calculations is shown in the normal way a computer would display it...with a heavily chunked progress bar, the end segment blinking, and stuck at a certain percent. No estimated time is shown.

Film

 * In the Iron Man movie, during the final upload to the Mark I suit, the progress bar very visibly speeds up and jumps toward the end.
 * Parodied in Office Space. When Peter tries to leave before Lumbergh catches him, it appears that his progress bar will finish in time. Then it restarts... and restarts again... and again...

Literature

 * One of the Alias novels has Sydney trying to upload a virus to a computer while pretending to be one of the spies for the Russian organization. Most of the tension of the scene is caused by the progress bar jumping back and slowing down at random, while the biggest threat to her cover is on her way to check the computer.

Live-Action TV

 * in Buffy the Vampire Slayer, Willow has to try doing research without magic after her brush with "addiction". When a progress bar stops about halfway, she reaches her hand up to speed it along with magic, but then it suddenly finishes loading.
 * Used and averted on Caprica. Several times characters get frustrated because a progress bar sticks at 95% or so before resuming and completing.
 * Apparently not even Higher-Tech Species are immune: at one point in Stargate SG-1, an Asgard progress bar is shown at around 75% for a few minutes, then abruptly increases to 100% in a couple of seconds.

Video Games

 * In Progress Quest, each and every progress bar moves straight from 0% to 100%. However, they're not actually representing progress, they are just fixed video effects.
 * Scan progress in the Metroid Prime games is always smooth, most likely because the scan data doesn't actually take quite that long to load. and maybe because its a fixed length animation that will always take that long to run.
 * Used hilariously in Modern Warfare 2. On one mission you're tasked with defending a computer system as it downloads files, but the 'time remaining' jumps all over the place as the transfer rate fluctuates. It flits between seven seconds and nine hours in one extreme example - this is clearly a humorous 'replication' of the Microsoft file transfer progress bar - the worst known example of an actual progress bar.
 * It gets more ridiculous in harder difficulties. In "recruit" (Easy) it's pretty close to the real version. In "Veteran" (Expert) it can reach up to several days and work slowly downward from there (just to make fighting off a full army of guys who can kill you in a few shots that much harder).
 * Product Placement in Wipeout went overboard when the commercial videos introduced in a post-release update played during the loading screen...and the loading bar would stop near the end as the video finished, whereas the bar had been perfectly accurate beforehand. The ads were since removed because players noticed this detail and felt anger about it. The game has was later updated to support new advertisements.
 * The first Wario Ware had menus modeled on a typical computer interface (the story being that Wario was programming the games, and you were working as a tester). When unlocking things, a progress bar would appear, and slow down and speed up while the new objects "loaded". The one for the title screen (if you don't skip the intro) moved at a constant rate, though.

Web Comics

 * Parodied in this Xkcd.
 * Played straight and later lampshaded in Homestuck. When Terezi's lusus hatches (and proceeds to be killed in a totally surprising plot twist) the doomsday timer activates, and it doesn't occur to Terezi at all to think about whether it brings about the apocalypse, or is simply the precisely calibrated timer to the end.

Web Original

 * On MSN Games, you see an ad before and sometimes interrupting gameplay. Below the ad is a progress bar that says "x% complete" and progresses at a constant rate. If the ad is not a video, the game will begin exactly when the bar reaches 100%. Of course this is not a real progress bar but a fixed delay disguised as one. (In the case of videos, the game will begin when the video finishes playing.)
 * There is a radio station named Lite 96 whose site has this when loading the radio stream.
 * In Star Harbor Nights, when an alien machine Hive Mind is trying to infiltrate a villainess's Elaborate Underground Base full of Phlebotinum waiting to be assimilated, the download progress bar keeps resetting and jumping around randomly, undermining her attempts to play Enemy of My Enemy with the government.

Western Animation

 * Parodied in The Fairly Odd Parents episode "Information Stupor Highway". While Mr. Crocker is uploading a file with a 1-month-old computer, the progress bar actually drops to -1%, among other tortures.
 * In Futurama, although the fake nose machine that also translates alien documents doesn't have a progress bar, it is stated that the exact process of translating a document could take anywhere from a few moments to a million years. The only way to tell when it's done? Two dings, though not like that... no, not like that either.
 * On the other hand, downloading the entirety of a human being's personality into a robot is measurable with an exact progress bar and apparently only takes about one second, as seen when Fry dates a robot clone of Lucy Liu.

Real Life

 * Mac OS X 10.4 "Tiger" has a startup progress bar that moves at a constant rate, using information about the duration of the previous system boot to determine how quickly it should move. Though technically it isn't a progress bar at all since it doesn't indicate the progress of the current operation, but rather how long it took last time.
 * 10.5 "Leopard" just tossed out this progress bar entirely, going straight from the gray Apple logo initially visible on boot to (after a couple of seconds) the login window.
 * Some ATMs in Germany ("Postbank") show progress bars which move at a constant rate... And then, when they're full, start from the beginning. What's the purpose of a progress bar, when it doesn't give you any information at all?
 * It does show that the system hasn't crashed. Without additional status text, though, it doesn't show the difference between "meaningful progress" and "stuck in an infinite loop".
 * For the most part, one is more likely to see a hideous inversion. If copying a diverse enough set of files in Windows (XP and earlier in particular), it's not rare at all to see estimates of "5 seconds, 1 hour 34 minutes, 0 seconds, 1 hour 56 minutes", etc, even if the transfer is halfway done.
 * Played straight in later versions of Windows with a much improved file copy dialog.
 * When doing something which might take a long time, but where the exact amount of time to complete is unknown, a fake progress bar is often used to show that something is happening. Such progress bars often start out fast at the beginning, but will keep slowing down towards the end.
 * Sometimes the progress bar is exact but misleading. Nautilus (a file manager for Linux systems) has a tendency to aggressively cache files when transferring a large amount of data. When copying from a fast device to a slower device, the progress bar will initially fill up rapidly, then slow down as the cache fills and becomes bottlenecked by the destination. Bonus points for when the progress bar fills up and disappears, but the transfer still isn't done (discovered when attempting to unmount the device) thanks to the write cache not being finished with its part.