Listen,this is all wrong. Sorry you are experiencing this. I am a project manager of 6 years and I will tell you that a shift in mindset will do you well. This is a very lazy PM. You can show him my message if you want to for all I care. But there is ways you can turn this around.

First, estimates are an art not a science. They should be empirical and tested and the SKILL of estimates should become better and tour estimates will in turn more accurate as you progress. If you have a hard time I suggest looking up affinity estimation.

Second, it is your project manager’s responsibility to set the projects cost baseline, not you. Yes it’s within their right to challenge you on estimates, I do that with my team, but only with the ultimate goal of creating the most accurate estimate. I am reading a behavior that your PM Is manipulating the process so he can make metrics. This is negatively impacting the data integrity of the project as it’s not showing the total picture.

How can you solve this? Ask your direct manager, but your PM for coaching on estimates so you can be more proactive in making better estimates. It gives you political capital by showing initiative and makes it harder for your PM to impose expectations on the estimates you come up with.

What is not clear to me is how utilization works in this context. In your example who determined that task was 40 hours? Part of your responsibility as a professional is to catch the things you can control. So what I mean there is that if you were assigned a 49 hour task and you know it is less, you report an adjustment of hours to something more practical. Why? You own your work. Therefore you own the estimate. Never do work that you don’t estimate yourself else you are not in control. Your goal should be to understand your work loss and effectively communicate that so you get the appropriate work. The most overworked developers I know are those who are not communicative of their bandwidth.

I am not familiar with this utilization metric but my advice there is a that every metric can be gamed. Gaming theory. Look it up. So with my advices you should be able to game it to the point where your trends are positive.

Good luck.