For a protocol that measures such small increments (mm) in changes to know if you’re going in the right direction, I think this is an important issue to address.
1. Day to day fluctuations
Can be effected by stress, mood, and just randomness. But we look for the bigger picture and the longer term trend here anyways.
2. Glans engorgement
The size of your glans can obviously (sometimes not obviously) affect your BPFSL measurement, especially post-workout using a vacuum cup device. But that is easily solved by squeezing the blood out of your glans for both your Pre and Post measurements.
3. Squeezing of the glans
I’ve noticed when you squeeze your glans, it gets longer, and can skew your measurement. I have small glans. My fingers tend to slip onto my glans the harder and longer I hold my stretch. And the more my fingers grip get to the middle of my glans, the measurement increases approx. 1-2 mm. Not too much, considering you’re consistently putting pressure on your glans from the get go as you’re pulling your penis. There’s no avoiding some squeezing of the glans when pulling, but as long as it’s consistent with the way you’ve been doing it, it shouldn’t be too much of a problem. I’ve just attempted to reduce the variability in this by using a small paper towel wrapped around my shaft where I usually grip around my penis, it has kind of helped in reducing slippage. Though slightly more painful because now my coronal ridge definitely feels more pressure from the force of the pull and also probably the paper towels texture. Not unbearably so, though. Maybe the silicone toe shields that I used to use for my extender work would be better for reducing slippage.
4. Glans angle
I don’t know how others measure, but I measure using a half OK grip. Meaning, my index finger wrapped around w/ palms up, and my index finger meets my palm on the other side to form the grip, with my thumb out of the way to measure better. What I notice is when I start pulling harder I inherently pull my glans up to get better leverage as I pull so my fingers don’t slip. But that does make my measurement smaller. So when I finally measure I straighten out my glans to where it should be pointing(straight out) and I get a proper measurement again.
5. Eyesight angle
When you measure from a ruler, if you look at the measurement from too far back or too far forward the measurement is skewed, not accurate. Too far back, measurement is smaller than it should be. Too far forward, measurement is bigger than it should be. The goal is to have your eyesight as perpendicular to the end measurement as possible. Measuring from your natural head position won’t work as you are looking at your ruler from an angle. To achieve a more perpendicular eyesight angle I do this by only moving the top half of my upper body forward as needed, so neck and upper back(shoulders) forward. I try not to move my lower body or back, as I may end up bending my hips and skewing the measurements even more.
6. Pelvis/Hip angle
Have your hips too forward, or too far back, or even slightly either way can affect your measurements by a few mm. The goal here is to have as neutral of a hip angle as possible when measuring and consciously staying neutral as you are reading your measurements. I do this by moving my hips VERY forward, and then retracting back until I hit what I feel is neutral. It gives me an idea and quick reminder of what it feels like to have my hips forward and once I lose that feeling I know I’m around the neutral zone. I also have a big mirror that I have on my side to double check. My posture isn’t the greatest and I’m actually used to having my pelvis/hips slightly in a more forward position hence why I do it this way.
7. Penis/Ruler angle
The newest factor that I’ve just recently realized about. Lowering the penis/ruler increases your measurements. Raising the penis/ruler decreases the measurement. The goal is to measure with your penis as parallel to the floor as possible. For this, I again use my big mirror on my side to help me out.
7a. Ruler Angle (a deeper dive)
As mentioned in #4, the modified OK grip helps me measure more accurately. My ruler is closer to and more in line with my penis for a more accurate measurement, with only my index finger in the way. Doing a normal OK grip I wouldn’t be able to measure because my thumb would also be in the way causing too much of a change in ruler angle, it would be angled too upwards. And we know any kind of angle change can skew measurements. The goal here is have your ruler IN LINE aka as PARALLEL as possible to your stretched penis when you measure. And of course, the closer your ruler is to your penis, the more accurate.
#7 has been a game changer for me, after incorporating my solution to it with the mirror I feel my BPFSL measurements are as accurate as ever.
Sure, I have taken an ego hit, but now I feel I can truly start from scratch and be more confident in my gains when I measure them going forward.