To a certain extent, you don’t know if what you are doing is right - and you have to accept that.
In my case it’s simple. I am putting more into my personal DC pension and not overpaying my mortgage, because my mortgage interest is low, but I get 40% tax relief on my pension contributions. (I’m a higher rate tax payer)
So if I put £500 into my pension tomorrow, it will be topped up to £750. Then that £750 will hopefully grow via stock market investment. £125 is added automatically (20%) and a further 20% / £125 you can either claim in an annual self assessment, or ask up front to have your personal tax code increased.
I can use a mortgage overpayment calculator to see how much interest I will save on my mortgage from a one off £500 overpayment. £100K mortgage at 4% for 18 years - it’s about £180 saved.
I have to take a chance that the mortgage interest rate won’t spiral, or that the stock market won’t crash and decimate my pension.
But on balance I’ll take £750 and potential to grow over £680.
OP, the first thing you need to do is find out what your current DB pension is due to pay annually, and from what age.
You have 2 parts: Final Salary and Career Average.
Final Salary will not mean the salary you have when you retire. It will mean the salary you were on when they closed the FS scheme. Your company will have told you the exact rule - mine for example, used your highest earning year of the previous three. Then, you don’t get that full amount. You will have an “actual rate”. Example for mine, is 1/60th. This means, for every year I worked before they closed the FS scheme, I accrued 1/60th of my final salary.
Real numbers:
My salary when the FS scheme closed: £30K
How many years had I contributed for? 10
So I accrued 10/60ths. That’s 1/6th of £30K, which is £5K.
So currently, I’m guaranteed to get £5K per year pension. It’s not linked to the stock market - my benefit is defined, it is known.
Now, £5K might be worth very little in 20 years time. So my scheme rules also increase it each year, by the lower of official inflation (RPI in this case) and 1.5%.
So I don’t know fir sure what will happen with inflation, but I assume that in 20 years time, I’ll have the equivalent of today’s £5K.
Career average has some similarities. I also have an accrual rate (1/70th). But I don’t know what my average salary will have been, by the time I retire. But I assume that it won’t decrease. At the very least, I hope it will increase with inflation.
Let’s assume I stay on £30K and work another 20 years. 20/70th accrued. £30K / 70 x 20 = £8571
So when I’m 67, I’ll have £5K + £8571 + about £8500 state pension.
Is it enough? Only you can decide. Do a budget. You won’t have work commute costs, but your heating when you’re at home not working might be higher. You can make an estimate.
Important to note, is that your Career Average amount is a projection. What if you can’t work 20 years? That’s why I’m saving in a private pension too.
If you have a DC (contributions) scheme its much harder - you don’t know what it will be worth in years to come, you’re dependent on the stock market. But you can still use websites to give you a conservative estimate. Although the stock markets goes up and down, over decades there is a general upward trend. Often, when you come to your last few years before retirement you move to less risky investments - to avoid losing a large amount with no time to recover. There’s lots more I could say, but hopefully that’s demystified it a bit.
I would say - YANBU to be confused. But YABU if you don’t address that, because there are lots of excellent websites and forums that will talk you through it. It may seem confusing but it really isn’t as bad as you think!