how is 2024 capital loss carryover calculated

You mean to carryover to 2025?   Yes.   

You get to first offset the loss against any gains you have each year so that can use more of it up.  Then after applying the loss to the current gains you can take a max loss of 3,000 (1,500 MFS)per year.  Turbo Tax does all the calculations for you.  Just enter the prior year carryover amount.

The current year carryover loss from the prior year is on schedule D line 6 & 14.

On the income page The 2024 column shows the carryover to 2025 (not your current loss for 2024).

Schedule D doesn't actually show the carryover amount. To find your  Capital Loss Carryover amount  you need to look at your  return schedule D page 2.  Line 16 will be your total loss and line 21 should be a max loss of 3,000.  The difference between line 16 and 21 is the carryover loss for next year.

There is also a Carryover Worksheet showing the carryover from the prior year and the current amounts.  Then there is also the Capital Loss Carry Forward worksheet showing the amount transferring over to next year.

In the Online version you have to save your return with all the worksheet as a pdf file to your computer to see Schedule D and the Capital Loss Carry Over and Carry Forward worksheets.

In the Desktop program you can go to Forms and find it in the list in the left column.

If you have a negative AGI or negative taxable income it will show up on 1040  BUT it won't reduce the carryover to the next year.