Capital gain/loss info from Schedule D is not transferring correctly to 1040, not the same number. Why is this?

If Line 16 of your Schedule D is a gain, this amount should transfer to Line 13 of your Form 1040.

If Line 16 of your Schedule D is a loss less than $3,000, the full amount of the loss should carry to Line 13 of your Form 1040.

If Line 16 of your Schedule D is a loss more than $3,000, only $3,000 should carry to Line 13 of your Form 1040.  The remainder of your loss will be carried forward each year until it is completely used up.  The maximum capital loss each year on your Form 1040 is $3,000.

If this doesn't address your question, please comment below so that I can assist you further.