Why it counts from today
Most reading calculators divide the goal by 365. That is the right answer in January and the wrong one for everyone else. Someone setting a 24-book goal in September, with three books done, needs more pages a day than the January number, and seeing the January number is how the goal quietly dies in November.
This page uses your device's date and counts the days left in the year, including today. The last box shows what the number would have been from 1 January, so you can see what starting late costs.