I would find option 1 and possibly option 2 off-putting in anything other than a game. I realise progress bars are a more-or-less rough estimate (ie. "they lie"

I would find option 1 and possibly option 2 off-putting in anything other than a game. I realise progress bars are a more-or-less rough estimate (ie. "they lie"). Just make it as good an estimate as you can reasonably do, and that's fine. For bonus points, display the underlying data in some way so that I can draw my own conclusions, supplanted with "sidechannel" information I am likely to have, e.g. previous experience with the process if nothing else. Extra bonus points if you make this information optionally visible so that I can tune it out if I don't need it and my mom doesn't get confused. I really like modern copy dialogs in that regard (and not-so-modern ones on decent file managers). If you can't make the estimate reasonable at all, don't make a progress bar and display progress in some other manner instead. E.g. if you are copying files, and you have no way of knowing how large each file is, consider simply putting down a simple count ("Files copied: x/y") and if at all possible some indication that the program is progressing at all ("Current speed: x MB/s"). Finally, please do try to add some kind of progress information for any task that can take more than a few seconds. It's incredibly frustrating to stare at a "busy" mouse pointer[1], having to guess whether an application has locked up or if it's just taking extremely long. If you get it wrong, you usually end up re-trying and being faced with the same situation. I have had to play detective around applications misbehaving that way, and having to use top, iotop, etc. to determine whether an app is using CPU, hard disk or network resources is both a lot of work and non-conclusive (not to mention beyond the capabilities of most users). (This started out as a short reply and ended up quite being a more general rant; the second time this has happened to me tonight. Sorry about that.) [1] Though terminal utilities are often just as bad, because they're not just designed with interactive usage in mind. However, each individual terminal utility tends to do less, which means complex process are broken down anyway, which yields some progress information.