What can and can't GPS do??

So I was wondering how far I walked today at work.  So much of it is back and forth or around in circles.  Yes, I know with a pedometer I will get a close idea how far I walked.  But if I'm going back and forth or in circles will Tom Tom or Garmin tell me how far I've traveled??  And what if I go 5-10 feet, back and forth...Will it pick that up??  Thanks for any and all info, Brian

If you work inside, a GPS is not so useful.  Outside, my GPS has show the difference between running different lanes on a track, so it would measure pacing short distances fairly accurately.

My Garmin will not work indoors but outdoors it is fairly accurate.
Jan

I find if you are only moving in a small space, whether outdoors or in, the Garmin just can't cut it. For example, I swam laps and it said I did .4 miles when I'd done 1.2.

Outdoors my garmin is very accurate and shows the difference between running on oneside of a trail or the other. For swimming they aren't so accurate because of the amount of time the unit may spend under water. 

For swimming the documents say that it uses a formla to calculate distance based on starting and ending points.  probably mixes in any points in between.

I like the gamin dashboard and analytics to let you track your performance too.

Just so you know they do make a foot pod attachment as well, so if you lose gps signal that can be used.  They also have a magnet sensor as part of the Cadence attachment that will work for bikes.
you input the size of the wheel and it calculates distance based on how many times the magnet passes the sensor.  So even when you get into an area where the gps signal may be non-existant, you can still calculate speed and distance.

Scott