Final grade calculator: what you need on the final exam to get the grade you want, the formula, a table for every current grade and exam weight, what to do when the number comes out over 100, and a printable sheet

"What do I need on the final?" is the question every student asks in the last week of the semester, and the arithmetic takes ten seconds once the three numbers are known: the grade going into the exam, the weight of the exam, and the grade wanted. This page does the arithmetic, shows the formula, gives the table for every target, and explains the two answers that confuse people: a number over 100 (the target is out of reach) and a number under 0 (the target is already safe).

Download the final grade sheet (PDF) (the formula, the grid of the score needed for every current grade from 60 to 95 and every exam weight from 10 to 50 percent, the letter scales and a planner; two pages, free).

The calculator

The formula

A course grade with a final exam is a weighted average of two things: everything before the final, and the final itself. If the final is worth w (as a decimal, so 25 percent is 0.25), the current grade is C and the final score is F:

Course grade = C x (1 - w) + F x w

Solve for F to get the score needed for a target T:

F = (T - C x (1 - w)) / w

With C = 82, w = 0.25 and T = 85: F = (85 - 82 x 0.75) / 0.25 = (85 - 61.5) / 0.25 = 94.0. For T = 80, F = 74.0. For T = 90, F = 114.0, which no exam allows, so a 90 is out of reach: the best this student can finish with is a perfect final, 82 x 0.75 + 25 = 86.5.

The one trap is the current grade. It must be the grade before the final, out of 100, with every other category already weighted in, which is the number on the gradebook the day before the exam. If the gradebook shows the final as a category with a zero in it, the displayed grade is already dragged down and is not C; use the grade with the final excluded.

What you need on the final: the table

The score needed on the final for a target grade, by current grade, for a final worth 20 percent (the most common semester-exam weight) and 25 percent:

Read across a row and the pattern is the whole lesson: with a 20 percent final, every point of target costs five points on the final, because the final is a fifth of the grade. A student three points short of the target needs fifteen more on the exam than their average; six points short needs thirty more, and that is where the table says "over 100".

When the answer is over 100, or under 0

Over 100 means the target cannot be reached with that final weight. The ceiling is C x (1 - w) + w x 100. Three things can still move it: a dropped lowest test score (which raises C), a replaced score, or extra credit, each of which is a question for the teacher this week, not after the exam. If none applies, the useful move is to set the target at the ceiling's letter and secure it: a student who cannot reach an A- can still lock in a B+ with a specific, reachable exam score.

Under 0 means the target is already safe: even a zero on the final leaves the grade above the target. That is rarer than students think; with a 20 percent final, a current grade must be at least 25 percent above the target for a zero to be survivable (an 87.5 going in is safe for a 70, not for an 80).

The letter scales

The calculator reports both scales most US high schools use. The plus-minus scale is Buffalo Public Schools' published scale; the 10-point scale without pluses is the North Carolina state scale (adopted for every high school in the state from 2015-16).

Your school's scale is in the handbook; some set an A at 94, some round 89.5 up, some do not. Where the calculator's letter and your school's differ, the percentage is the number to trust.

Semester exams: two quarters and a final

If the "final" is a semester exam and the semester grade is two quarters plus the exam (40/40/20 in most district policies), the current grade is the average of the two quarters and the weight is 20 percent. The semester grade calculator has that version with the other splits schools use. For a course grade made of weighted categories (homework, quizzes, tests), the weighted grade calculator does the first step. For the GPA those grades become, the high school GPA calculator.

What to do in the week before the final

1. Run the number once, honestly. A student who knows they need an 84 studies differently from one who thinks they need "a good grade": the number tells them whether every section matters or only the hard ones.
2. If the number is 90 or above, go for coverage, not depth. A final is usually cumulative and the marks are spread across every unit; the fastest points are in the units studied longest ago, which are the ones forgotten. Redo one problem from each unit before any deep work.
3. If the number is 75 to 90, find the two units with the most marks and the weakest recent test. Past tests are the syllabus for the final; the questions missed on them are the questions most likely to be missed again.
4. If the number is over 100, ask the teacher one question on Monday: whether anything in the current grade can still move. Then set the reachable target and study for that.
5. The night before: no new material; one timed set of mixed problems, early; the formula sheet or allowed notes prepared; sleep.

Download the final grade sheet (PDF) (the formula, the grid for every current grade and exam weight, the letter scales and a planner; two pages, free).

Where to get help

A 1-on-1 online class with a tutor who holds a master's in mathematics and teaches the US curriculum, Algebra 1 to AP Calculus, chemistry and physics, at 7 am before school, after 4 pm and on weekend mornings, US time, for US$10 to $13 an hour: the grade worked out above read together in the free 30-minute first class, the category or the course where five more points cost least found, and the term spent on exactly that. How online tutoring from India to the USA works, or the 1-on-1 online tutoring page.

Questions parents ask

See how we teach this, 1-on-1 online →