I have the world's tiniest pinky. Welp.

Abandon all hope and buy a mandolin.
Just kidding.
Keep trying.
Do some stretching on your fingers. This may help.

 

Don't use your pinky.

 

Be glad it's your pinky and not...oh, nevermind.

You need to do some stretches before practicing. Work on correcting that concave bend. Make every effort to bend it correctly while fretting, no matter how slow you have to go. You'll speed up in time.

You might also try some forearm exercises. Those muscles play a big part in what your fingers do.

 

@Norm Stockton in his instructional videos shows you taking your index finger and ring finger and pulling them down into your hand, stretching your fingers into your palm. Also taking your middle finger and your pinky and pulling them down into our palm. Stretching them for a few seconds, release. Keep switching fingers.
Also before playing I think he recommends tapping the pads of your finger tips into the pad of your thumb tip. I do this by tapping my index finger about three times, moving to the next finger, all the way down to the pinky and then back up to the index finger. This will warm your hand up and also strengthen your fingers. No extra accessories needed.

 

Bing is your friend:

hand forearm stretches - Bing

 

It is possible to play bass with small fingers. You would need to adapt your technique though. I believe that pivoting will be essential.

 

I'm missing the padding on the tip of my playing pinky - accident as a child. So it's about 1/4" shorter than the normal pinky on my plucking hand.

I played for many years without it thinking I'd never adapt, but one day I did start learning to play with it and now, though it's the runt of the litter, it's a regular finger along with the others.

Basically you just have to keep practicing. My hand is always ever so slightly out of position when using the pinky because half of it is missing, but I've been able to adapt to it and use it without trouble.

I do find that I prefer thinner necks, even though I played 6 string as my main instrument for a few years on a big ol fat neck. So you might think about a jazz bass dimensioned neck for a while while you're getting your strength up, but I wouldn't think that's really required. Just keep playing and practicing and you'll eventually adapt.

L

 

It's a strength and coordination issue. You fix it by forcing yourself to use it even though it doesn't feel natural and comfortable.. enough time spent doing so and it will feel like second nature.

There are some exercises that might not sound very musical but will build your dexterity and strength.. throw in the metronome for good practice and time development while you do it.

For a week to a month, every time you sit down at home to pick up your bass, spend 2-3 minutes just playing 4 note patterns up and down the neck. like E string - 1 2 3 4 (frets, index to pinky), then A string 1 2 3 4, then D then G.. then on the G, 2 3 4 5, same on the D, same on the A, same on the E, do this up to the 12th fret, then back down.

Takes a few minutes, do it at the start of any practice session.. it's a good warmup and it'll get easier each time, you'll be able to speed up the metronome and your pinky will get stronger... and you might even learn to use it to save yourself some stretching when you get to 5ths and octaves on the lower parts of the fretboard.

There are other exercises.. spider exercises, as well as alternating 1 3 2 4 instead of 1 2 3 4, or 1 2 4 3 or 2 1 3 4. All of it simply gets you used to your fretboard and using your fingers to manipulate the strings upon it.

 

Instead of trying to force your pinky into some sort of strict, formal technique, just adapt your playing style to suit your body.

 

One alternative is to study Geddy Lee's techique. He keeps his fingers close together, and doesn't use his pinky very much.



Les Claypool is a big Geddy Lee fan, and uses a similar technique sometimes:



My point being, you do not need to stretch and contort your fingers like crazy spider legs, in order to be a top-tier musician! Study videos of your favorite players, in real-world situations. When you watch the top pros on stage, usually their hands are comfortable, not tense. Relax and please don't hurt yourself.

 

Victor Wooten stands about 5 foot nutn. He has literally walked under my outstretched arm. (I'm 6' 2".) His fingers are very short compared to mine. He is, however, human.

So there's hope!

 

lots of people don't play with their pinkies - is there a reason, OP, that you feel the need to do so?

btw, my pinkies each measure about 2 inches. i used to use them sometimes, but over decades they didn't get helpfully stronger, so now i don't use them when playing.

 

It sounds like someone's convinced you that one-finger-per-fret is the only correct way.
This is not the case.
Don't injure yourself unnecessarily. You can play pretty much anything just as well with three fingers.

 

Make sure the action on your neck is set up on the low side. Try a low tension round core string for less resistance.