Estimation is ultimately a futile effort. Software, more or less, is like writing poetry. Or solving mathematical proofs. It takes as long as it takes, and it’s done when it’s done. Perfect, or imperfect, estimation won’t change how long it takes to complete the work. If that sounds horrible to you, then go do something else.
From 25 years of professional development, I can safely say that estimation is a waste of time. Seriously, don't do it
If only life was that easy ;)
There are 2 resources I consider valuable in terms of software estimation:
I cannot recommend them enough - both for devs, as well as tech PMs.
It really is that easy. I wasn't joking
You'll get things done faster, and write better code
A good quote on the subject:
Taken from here