GrowthTrack Penis Data Reveals: How large is the average BPEL - BPSFL gap? How thick is the average fat pad?
This one is going to be pretty straight forward folks. We begin with some brief terminology for users new to PE:
- BPEL (Bone Pressed Erect Length): Length of the erect penis measured with a ruler pressed firmly against the pubic bone, ensuring consistent tracking by excluding fat pad variations. It is the measure used in scientific studies of penile length, the only reliable measure, king of length measurements.
- NBPEL (Non-Bone Pressed Erect Length): Length of the erect penis measured without pressing into the pubic bone. Less than “usable length” since the fat pad compresses. A vanity measure more than a useful measurement for PE. By all means track it, but don't make it your only form of length tracking since it is such an unreliable measurement.
- BPFSL (Bone Pressed Flaccid Stretched Length): Length of the penis in a flaccid but fully stretched state, measured with the ruler pressed into the pubic bone and with the penis stretched with significant force. A good early indicator of length gains since it will tend to increase months before BPEL gains manifest.
Ok, with that out of the way, let's see the data.
How do people's BPEL compare to their BPSFL?
The average gap between stretched flaccid length and bone-pressed erect length is 8 mm (0.3 inches).
Very few people have longer erect length than stretched flaccid (the negative values toward the left side of the diagram), but apparently it happens.
I think these users must probably just be measuring their stretched flaccid wrong - you are supposed to stretch pretty hard. At minimum with 400 grams of force (0.88 lbs) according to conventions in medical literature, but mostly we recommend pulling "pretty fucking hard indeed".
The most common difference is 6mm (0.24").
I really like seeing roughly bell-shaped diagrams like this; it means people are probably tracking right. Biological traits tend to neatly fall into bell curves. This is a large dataset - a hair less than 500 guys - so we can be pretty confident this gives us a good picture reality.
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Ok, but do longer penises also have more ability to stretch? If you take a long piece of rubber band, and a short length of the same rubber band, the longer piece can be stretched a longer length, even though both can be stretched the same /percentage/ of its own length. Does that work the same for penises?
Yes, for all 497 BPEL-BPSFL-pairs we have registered in the app, we see that there is a pretty clear correlation: r = 0.451 · r² = 0.203 · p = < 0.001
Longer penises can also stretch a longer distance, but there is clearly a wide range of variability. (The Y-axis here is the "stretch-gap")
And now we get to the most interesting number...
How thick is the average fat pad?
For the 150 guys for whom there is both BPEL and NBPEL data in the app, the mean fat pad thickess is 21.3 mm or 0.84 inches.
80% of users have a fat pad between 11 and 34 mm. It is a rare occurrence indeed to have a fat pad thinner than one centimeter.
Relatively few users in the app track NBPEL, which is why we only have 150 data points. I think this is a good sign, because it means users prioritize the measurements where you get better precision - bone-pressed.
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Short and to the point this time, since this doesn't involve any advanced statistical analysis - it's just raw biometrics. Were you surprised by any of these data?
//Karl - Over and Out
Posted Jul 10, 2026, 7:32 PM UTC