Did some testing with my old Garmin where the Ftp app is installed. Did my ride and did some testing. I found out that there was a difference between what the app calculated and what Xert makes of my ftp on the platform. Any changes I should do of is this normal?
Hi Sven,
This is perfectly normal. WMFTP is a lite version of Xert’s full online suit, designed to showcase some of the power of Xert without requiring a full subscription. Because the algorithm behind WMFTP is slimmed down, the value can differ from Xert, especially if you haven’t performed a (near) peak power sprint since installing the WMFTP data field.
Hi,
I’ve notice a rather significant difference today too. WMFTP showed 10 Watt more on the Garmin than the after work analysis on the web. Unfortunately 
I had a “breakthrough” in the MPA datafield and TTE of -54 secs for 300 watt.
Is WMFTP of any use when you have a subscription? Or better only use the MPA app?
( further on the ride my Garmin Edge 1030 crashed, power off, 3 times in 10 km )
If the WMFTP doesnt have data from a near-maximal sprint, then it might be underestimting your PP and conversely overestimating your TP. Try throwing in a PP sprint as well.
As mentioned earlier, they will likely vary by a little bit because the way the system computes TP and the way that WMFTP computes FTP are quite different. Still interesting that they end up so close without requiring a 20 min test, eh? 
Used WMFTP again today in a hilly ride in the regio of Tour of Flanders so enough PP type of sprints.
WMFTP indicated 20 Watts more then the application ( 274 / 254 ), a difference of > 7%.
Had a small breakthrough of 3 watts on the application.
Your HIE is a little bit higher than the typical range for your PP, based on our article here. Which is okay, it doesn’t make it wrong.
The WMFTP app doesn’t try and uncover TP and HIE independently (or care for the relationship between PP and HIE), which is why you’re likely seeing a discrepancy between the app and the online system.