Power differences between Zwift and Garmin

General Discussion
1

I have a Stages left crank power meter and a garmin 530 head unit. When I set up my ride in Zwift I choose the Stages power meter.

While riding the Garmin head unit will display higher watts by 20 - 45 watts from what Zwift is displaying and recording.

Any thoughts why there would be such a difference.

2

One thing that I can think of is you may have 3 second averaging on for zwift and instantiations for the Garmin.

You can use the Zwift power data analysis tool to look at the data.

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3

Gerrie - I already had the Garmin head unit on 3 second averaging. The stages power meter is in the left crank. When I pedal the power/force should be the same for both the Garmin and Zwift is my thought. I don’t know how they are getting 2 different reading from the same power meter.
Thanks

4

Try the analyzer that will help to quantify the difference.

Do you use ANT+ of Bluetooth for Zwift?

5

I use Bluetooth for Zwift and display it on my Ipad.

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7

I have an SRM power meter and a garmin 510 and I have the same problem. I use Ant + and configured every 3 seconds in zwift and in the garmin. any solution? regards

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8

Did anyone ever get an answer on this? I have the same problem with an sram (quark) power meter.

9

Also have tge same problem, zwift under records my max power by 100w or more regularly, I have used left crank stages and now assioma duo, still the same under recording from zwift, Garmin connect, Strava, and training peaks are all the same numbers just zwift is low.

10

I have the same issue. I use a quark and a Garmin 1030. Zwift consistently shows my power as 30-40 watts lower than my Garmin average. I contacted Zwift and they didn’t respond.

11

Hi @michael_diamondstein

Welcome to the forum.

they should read the same. You can record the ride on your garmin device and then use Zwift power to analyze (compare) the two.

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12

wont that only work if they have 2 power sources? what if they are using a crank based power meter on a dumb trainer that wont give them any comparable data

be helpful if people gave what their setup was

13

The idea is to see if the power profiles match, I would assume it will be exactly the same.

Sometimes it does look like the Garmin and Zwift show different numbers because of different updating. but if you have the raw data you see it is the same.

14

Just out of curiosity I may try this. The last post in this thread though, before it was resurrected, mentioned that max power was listed differently. Isn’t “max”, well, max?

15

All about timing…my Zwift and Garmin (F3) can be off by a few to a couple dozen watts at the peak. After all, I am only holding it for a fraction of a second.

Next we will need a synchronous clock like the audiophiles think they need.

16

I can conceive of timing differences, but universally leading to one of the devices always reporting higher than the other? You might think that there could be swing ‘in favor’ of either device, on a random basis.

17

I will have to try this connection scheme and check. I always connect my F3 to my P1s in case my trainer takes a dump…and to check calibration. Next ride, maybe tonight, I will connect both Garmin and Zwift to my trainer and see what arises.

99% of the time the P1/F3 combo is lower than my trainer/Zwift combo. Usually pretty close in the 160-240 watt range (vast majority of the time) but does deviate at each end of the power curve. Sometimes only a few watts (<10) but sometimes pretty far…50-60 watts at the top end (600-900 watts).

18

A couple of points I can think of.

  1. Zwift on your computer/ipad etc and the Garmin will both process the information at different rates, so they will never show the same numbers at the same time. This is due to the different processing power of the components in each device.
  2. I have my Garmin set to not count the zeros in my power and cadence (when you stop pedalling those pauses aren’t counted in the overall averages) whereas Zwift counts the pauses in pedalling in the overall averages, so if you compare a recording done by your garmin to that of a power meter running on your Garmin, the averages will be much lower on Zwift.
19

Unless you are unbalanced. I ride, on multiply power meters, at 45/55