Your current grade should cover everything except the final. The weight is how much the final counts toward the course.

The formula

Your course grade is your current grade weighted by everything except the final, plus the final score weighted by its share. Solving for the final score gives: needed = (target − current × (1 − weight)) ÷ weight.

Example: with an 86 now, a final worth 25%, and a goal of 90, you need (90 − 86 × 0.75) ÷ 0.25 = 102%. That means a 90 isn’t reachable without extra credit. Check your syllabus, since some instructors drop a low score or round grades.