How the final grade calculator works
The final grade calculator splits your course grade into two parts: everything you have done so far, and the final exam. If the final is worth 20%, your current grade counts for the other 80%. The score you need is whatever fills the gap between that 80% share and your goal.
score needed = (goal − current × (1 − w)) ÷ ww is the final’s weight as a decimal: 20% → 0.20. Current and goal are percentages.
Worked example
Current grade 88%, final worth 25%, goal 80% (a B on a 10-point scale).
Your work so far is worth 88 × 0.75 = 66 points of the final course grade. You need 80 − 66 = 14 more points from the final, and the final carries 25 points, so 14 ÷ 0.25 = 56%.
Check: 88 × 0.75 + 56 × 0.25 = 66 + 14 = 80. ✓
The calculator also shows the score needed for every letter grade at once, on a whole-letter or plus/minus scale, and an optional “if I score…” box that runs the math forward: type the score you expect and it returns the course grade you will end with. “Copy link” saves your numbers in a link you can reopen or send to a study partner; nothing is stored on our side.
How much can the final change your grade?
A final can move your grade by at most its own weight: a 20% final can add or remove up to 20 percentage points between a 0 and a 100 on the exam. The table shows the lowest and highest course grade you can finish with for common starting points.
| Grade now | 10% final | 15% final | 20% final | 25% final | 30% final | 40% final |
|---|---|---|---|---|---|---|
| 95% | 85.5–95.5 | 80.8–95.8 | 76–96 | 71.3–96.3 | 66.5–96.5 | 57–97 |
| 90% | 81–91 | 76.5–91.5 | 72–92 | 67.5–92.5 | 63–93 | 54–94 |
| 85% | 76.5–86.5 | 72.3–87.3 | 68–88 | 63.8–88.8 | 59.5–89.5 | 51–91 |
| 80% | 72–82 | 68–83 | 64–84 | 60–85 | 56–86 | 48–88 |
| 75% | 67.5–77.5 | 63.8–78.8 | 60–80 | 56.3–81.3 | 52.5–82.5 | 45–85 |
| 70% | 63–73 | 59.5–74.5 | 56–76 | 52.5–77.5 | 49–79 | 42–82 |
Read across from your current grade. If your goal sits outside the range in your column, no exam score will get you there (above the range) or you are already safe (below it). For full lookup grids by letter grade, see what do I need on my final.
Find your final exam weight first
The final’s weight is the single number most students get wrong, and it changes the answer more than anything else. Look for it in your syllabus or gradebook in one of these forms:
- A percent: “Final exam: 20% of the course grade.” Use that number directly.
- Points: “Final exam: 200 of 1,000 points.” The weight is 200 ÷ 1,000 = 20%. Your current grade is the points you have earned divided by the points graded so far.
- A shared category: “Exams 40%” with a midterm and a final in it. If the two exams count equally, the final is about 20% of the course. If the category has several parts, enter each one in the weighted grade calculator instead.
- A semester exam: many high schools average two quarter grades and an exam, such as 40% / 40% / 20%. The semester grade calculator is built for that layout.
Points classesIf your teacher grades by total points, the final does not have a fixed percent weight until you know the total points in the course. Divide the final’s points by the course total to get w.
Common final grade mistakes
The most common mistake is using the rounded grade from a report card instead of the exact percentage in the gradebook. On a 20% final, a 2-point difference in your current grade changes the score you need by 8 points. Other frequent errors:
- Typing a points weight as a percent. A 150-point final in a 600-point course is worth 25%, not 15%. You can type 150/600 straight into the weight box.
- Forgetting work that is still ungraded. Missing homework or a late project changes the current grade before the final; enter every category in the weighted grade calculator.
- Using the wrong cut-off. On a plus/minus scale an A usually starts at 93%, not 90%. Pick the plus/minus option to see the A−, B+ and the other steps.
- Assuming the final replaces nothing. If your teacher drops the lowest test or lets the final replace it, your current grade changes too.
When the answer is over 100% or below 0%
A result above 100% means the goal is out of reach without extra credit, even with a perfect exam. Try the next letter down: the calculator lists every letter, so you can see the highest grade still possible. A result of 0% or less means the goal is already locked in, and even a blank exam keeps you there. Some courses require you to sit the final to pass at all, so check the syllabus before you skip it.
Your letter grade also depends on your teacher’s cut-offs. A common U.S. 10-point scale puts an A at 90–100, a B at 80–89, a C at 70–79 and a D at 60–69,[2] while plus/minus scales split each band again (A− from 90, B+ from 87).[1] The letter grade calculator converts any percent on either scale.
How we check this calculator
Every formula on this page is covered by automated tests that run before each update, including a round trip: the score the calculator says you need is plugged back in and must give exactly your goal. The worked example above (88% now, a 25% final, a goal of 80% → 56%) is one of those tests.
- 13 November 2026: added the grade chart, the grading-scale picker, points weights (200/1000), shareable links and the “All my finals at once” planner on what do I need on my final.
- Known limits: the calculator assumes the final is one fixed share of the grade. If a final replaces a test or a category, recalculate the current grade first.
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Frequently asked questions
How do I calculate what I need on my final?
Multiply your current grade by (1 − final weight), subtract that from the grade you want, then divide by the final weight. With an 80% now, a 30% final and a goal of 85%: (85 − 80 × 0.7) ÷ 0.3 = 96.7%.
How much is a final exam worth?
It depends on the course. Your syllabus states the weight, either as a percent of the grade or as points out of the course total. Finals worth 10% to 30% are common, and some college courses put 40% or more on the final.
Can a final exam drop my grade a whole letter?
Yes, if the final carries enough weight. A 20% final can lower your grade by up to 20 points if you score 0, and a score of 50% on it lowers an 85% to 78%.
What if my class uses points instead of percentages?
Divide your earned points by the points graded so far to get your current grade, and divide the final’s points by the course’s total points to get its weight. Then use the calculator as normal.
What is my final exam percentage if I scored 15 out of 20?
75%: 15 ÷ 20 = 0.75. You can type 15/20 directly into any score box on this site.
Does the calculator round my grade?
No. It shows exact values to two decimals. Some teachers round 89.5% up to 90%; your syllabus says whether yours does.