Treadmill pace and distance vs outdoors

treadmill pace isn't necessarily accurate. I would gauge effort using your HRM and RPE.

Quality treadmills can be quite accurate. Some people say to add 1% incline to make up for the motor but others don't. It all depends on your particular treadmill plus how you run. Treadmill running is by nature a but easier because of the consistency and lack of wind etc.

Foot pod accuracy is a separate issue entirely.

I vote for setting it 1% up.  I have found that get's my HR up to the same point going the same speed on my typical outdoor run and under typical running conditions.

Treadmill calibration can be variable, unfortunately. Most home-owned TMs will be fairly accurate, but even a 2% pace discrepancy can mean a missed PR in a 5k, by 20seconds or more. 

If you run on various gym different treadmills at different facilities, you'll see this in extremes - I've had TMs that on 0% incline have me running a 5:00min/mile or a 8min/mile for a true 7:00min/mile effort for me (I'm very good at RPE of my true paces from many years of running on a track). More typically though, TMs I've used vary between what I think is 10-40sec/mile from actual real world pace on a track. 

I find it best to just recalibrate your TM expectations by HR and/or RPE for training, and use a grain of salt when estimating outdoor performance - I've routinely do actually do outdoor field test 5ks and 10ks to check up on my treadmill training work, but now since I own my TM, I have enough outdoor numbers such that I know that if I can do "x" pace for "y" distance on TM, it will roughly equate to "Z" pace outdoors in a race. 

A 35% variation shows that SOMETHING is miscalibrated. It's either the footpod or treadmill, take your pick. Likely a combo of both. 

Footpods, when properly calibrated, are typically 95%+ accurate, whereas TMs, especially gym TMs that get heavy use, are often quite off. 35% is a lot, yes, but I routinely see differences of 1:00min/mile, which is a big deal when you're running 6 min/mile on the TM, and it's showing 5 or 7.

You might THINK your treadmills are all accurate at your gym, but odds are they are all variable my a small amount. I don't know of any gym that routinely tests the calibration speed of their TMs, unfortunately. In my local YMCAs, which all use the same LifeFitness commercial TMs, I definitely see as much as a 1min/mile variation in the paces amongst TMs even in the same facility. 

Unfortunately, commercial gyms don't care about how accurate their TMs are. You can complain to them, and they'll probably tell you, 'sure we'll do it' -but then do nothing.

Clearly your footpod did not accurately calculate the distance you might have covered.  Probably because your stride is not quite the same on the treadmill. 

The treadmill might have been somewhat off too, but I will bet it was much closer to the speed you were actually running. 

I find it funny that many people believe this, yet put their full faith in GPS and/or footpods.  I agree that the treadmill may not be 'really accurate', but a decent treadmill is going to be MUCH more accurate than either of the other two in most cases.