October 30, 2014

Calibrating a foot pod to a Garmin Forerunner 620

My sister wanted some help calibrating the foot pod for her Garmin 620, so I spent a while this morning searching for any info I could find. I've tried to get an answer from Garmin several times over the past year about it, but I've never gotten a response (I love my Garmin, but their customer service is terrible). I knew that there was a calibration factor (a number that is factory set at 100.0), but I had no idea what that number meant. So this morning, I was determined to find out.

I calibrated my foot pod a long time ago with the 910XT, but I've noticed that it's been "off" lately when I've used it, showing that I'm going a slower pace than I actually am running. After a ton of searching online, I found out how to manually calibrate the foot pod (the newer Garmin Forerunners don't have the calibration tool built in), and I actually understand what the number means now.

If anyone is interested, to calibrate the foot pod to the Garmin Forerunner 620:

1) On the watch, go to Settings - Sensors - Foot Pod - Calibration Factor
2) If it's not already, set it to 100.0% (this just makes the math easier later)
3) Choose a measured course to run (ideally, this would be a 400-meter track, but you could also use a treadmill if you want to calibrate the watch to read the same as what the treadmill shows).
4) Start the watch, and run 800 meters (you could run farther, but make sure to do at least 800). Note: Run the 800 meters as measured by the track or treadmill--just ignore the watch for now, because it probably won't be accurate. Stop the watch when you're done.
5) Take note of the distance that is shown on the watch.
6) Use this formula to figure out the calibration factor:
    Actual distance in meters/(recorded distance x current calibration)
For example: You run 800 meters on a track, but the Garmin showed that you ran 0.48 miles. Convert the miles to meters (I just use Google to do that for me), and you get 772 meters. So you plug in the numbers... 800/(772 x 1.000) = 1.036. So the new calibration factor needs to be changed to 103.6% (see step 1).

The number just shows that you ran 103.6% of what the Garmin was showing (slightly faster).

That was a whole lotta math, but you know I love numbers, so it was fun for me ;)

I had three miles at goal race pace on the schedule today. My goal is a sub-2:00 half-marathon, which is a 9:10/mi pace. So My goal for today's run was to stay between 9:00 and 9:10 per mile. (When you run a half-marathon, the total distance is usually longer than 13.1 miles, due to weaving and not hitting the course tangents. So I like to have a small buffer in my pace, aiming for about 5-10 seconds per mile faster than needed.)

I wanted to calibrate my foot pod, so I went to the high school track. I decided to run 800 meters as a warm-up, and calibrate the foot pod with that number, then run my 3-miler at goal race pace. I ran at an easy pace for the calibration, then cleared my Garmin and started the goal pace run (using GPS, not the foot pod).

My legs were tired today! I'm not sure doing cross-training the day before a goal pace run was a good idea. I wasn't sore (well, except the bones in my butt! They feel bruised from the seat of my bike), but my legs were definitely feeling tired. I did really well at holding pace, even though it felt very hard today.

I'd like to go back to the track and use the foot pod rather than GPS, just to see how accurate it is when I run at all different speeds. Maybe I'll do that next week. I'm hoping to not have to use the treadmill much this winter, like I did last winter; but if I do, I'd like my foot pod to be accurate.

I've been really consumed with a missing persons case for the past few days. On Saturday night, there was a house a few miles from me (actually, it's on my favorite long run route) that had a Halloween party. It was a huge party, with upwards of 600 people there. The house is surrounded by cornfields and woods, and it's a pretty rural area. There was a 22-year old woman named Chelsea Bruck at the party who went missing sometime around 2:00 a.m. Sunday.

She didn't have her cell phone or purse with her (she left them in a friend's car). Supposedly, someone saw her talking to a guy near where the cars were parked, so he is now a person of interest. But there are truly no real leads on this case--it's like she just vanished.

I've been seeing several news vans there all week, and they've had search parties and candlelight vigils. Here is the poster they've been handing out (click to enlarge):

The police have also released a sketch of the person of interest:

I didn't know her, but because this was so close to my house, I've been following the case really closely. Her case was on Nancy Grace tonight, so hopefully they'll get some new leads. I just really hope that Chelsea is alive and comes home safely! It's so scary how someone can disappear just like that.


  1. I hope they find her. :(

    If I ever get a Garmin I know where to come to figure it out lol.

  2. I have that Garmin on my Christmas list, but one of the features i was excited about is the built-in accelerometer so that I wouldn't need to buy a foot pod. Did that functionality not work as well as they've advertised?

    1. Diane, that was one of the features that sold me on the Garmin 620 as well! But I later learned that you actually DO need the foot pod for accuracy. Here is an article that explains it: http://www.prweb.com/releases/2013/12/prweb11402622.htm
      The way Garmin worded it in their advertisements was deceiving, unfortunately.

    2. Agreed, the built in accelerometer sucks (well, I'm sure it's fine, you just can't glean that much useful data from just your cadence). Unless you always run the exact same pace, it's not going to be accurate. It just recently said I was doing an 8:58/mile pace at an indoor track when I was actually doing a 7:55 pace.

    3. That's annoying but good to know now rather than later! Thanks!

  3. That is scary. There has been a 15 year old missing in Arkansas for over a month and since the police have classified her as a runaway they are hardly trying. Her family is beside themselves.

    I remember calibrating a foot pod a long time ago for the only Garmin I ever had. It was a pain! I did it on the track too but I swear the correct calibration didn't last long. It always told me I went longer than I really did. At least it was good for my ego.

  4. Hopefully they find her! That is scary to think about. There was a college student in my old college town that went missing this last week. It was the college's homecoming so there was a lot of drinking...unfortunately they found his body in a grain bin. Not sure why he went up there, more than likely just drunk thinking, but it was sad.

  5. "You run 800 meters on a track, but the Garmin showed that you ran 0.48 miles. Convert the miles to meters (I just use Google to do that for me), and you get 772 meters.

    Why not just switch the watch to metric? (saves Googling!)

    1. Well,because metric sucks. :)

      I did find it funny that the formula was written as 800/(772 x 1.000) = 1.036

      772 x 1.000 is still 772 so why not just put 800/772=1.036

      The best way to do a manual calibration is to initially set the watch at 1.000 anyway

    2. Miles or meters, the math is the same. According to this post, she's basically saying that Known Distance divided by Garmin Distance and multiplied by the current calibration setting (100 in this case) = that same percentage for any unit.

      Example 1: 1 mile / 1.07 miles X 100 = 93.5%

      And converted to meters:

      Example 2: 1609.34 meters / 1722 meters X 100 = 93.5%



I used to publish ALL comments (even the mean ones) but I recently chose not to publish those. I always welcome constructive comments/criticism, but there is no need for unnecessary rudeness/hate. But please--I love reading what you have to say! (This comment form is super finicky, so I apologize if you're unable to comment)

Featured Posts

Blog Archive