Score needed for each letter grade
With 85% so far and a final worth 20%:
| Course grade | Needed on the final |
|---|---|
| A (90%) | 110% (out of reach) |
| B (80%) | 60% |
| C (70%) | 10% |
| D (60%) | Already reached |
Letters use the common US scale (A from 90%, B from 80%, C from 70%, D from 60%). Your school may use another, or plus and minus grades.
The formula
Your course grade is a weighted average of the grade you have so far and the final exam:
Here w is the final's weight as a decimal: a final worth 20% has w = 0.2, so everything before it counts for 0.8.
Worked examples
- What do I need? 85% so far, final worth 20%, aiming for 80%. You have 85 × 0.8 = 68 points banked, so you need (80 − 68) ÷ 0.2 = 60% on the final. A perfect final would give 88%, so an A (90%) is out of reach: it would need 110%.
- What will my grade be? 72% so far, final worth 30%, scored 90%: 72 × 0.7 + 90 × 0.3 = 50.4 + 27 = 77.4%.
Before you rely on it
The formula assumes the final simply counts for its weight on top of everything else. Some courses work differently: the final replaces your lowest test, a minimum score on the final is needed to pass, or grades are rounded up from, say, 89.5%. Check the syllabus or ask your teacher, and treat the result as a guide.
Questions people ask
How do I calculate what I need on my final?
Multiply your current grade by the share of the course that is not the final, subtract that from the grade you want, and divide by the final’s weight. With 85% so far, a final worth 20% and a target of 80%: 85 × 0.8 = 68, then (80 − 68) ÷ 0.2 = 60%.
What if the calculator says I need more than 100%?
Then the target can’t be reached with the final alone unless your teacher gives extra credit. The working shows the best grade you can still get with a perfect final; with 85% so far and a final worth 20%, that is 88%.
What if my grade is weighted by category?
Use your current overall grade as your teacher’s grade portal shows it, since that already combines homework, quizzes and tests with their weights. If the final replaces a category or your school drops the lowest test, the simple formula here won’t match, so check the syllabus.
Is 90% always an A?
No. 90/80/70/60 is the most common US scale, but many schools use plus and minus grades, a 93% cut-off for an A, or different scales entirely. Enter the exact percentage your syllabus needs as the target.
Can the final lower my grade?
Yes, if you score below your current grade. A final worth 20% scored at 50% with 85% so far gives 85 × 0.8 + 50 × 0.2 = 78%. Use “What will my grade be?” to try different final scores.