The formula
Required final score = (Desired grade − Current grade × (1 − Final weight)) ÷ Final weight
All values are percentages expressed as decimals. Example:
Current grade: 82%
Final exam weight: 25%
Desired grade: 90%
Required = (0.90 − 0.82 × 0.75) ÷ 0.25 = (0.90 − 0.615) ÷ 0.25 = 0.285 ÷ 0.25 = 1.14 = 114%
A required score above 100% means the target is no longer achievable — time to reset expectations.
What the result actually tells you
If the required score is below 70%: You have breathing room. You can afford a bad final and still hit your target.
If it's 70–90%: A solid but achievable performance keeps you on track. Study normally.
If it's 90–100%: You need a near-perfect final. Prioritize this course above others this week.
If it's above 100%: Reset your target grade. Run the formula again with a lower goal to find out what a realistic final score achieves.
The "what-if" version
Sometimes you don't have a target grade — you just want to know what a given final score does to your overall grade.
What-if grade = Current grade × (1 − Final weight) + Final score × Final weight
Example: Current grade 85%, final worth 30%, you score 70% on the final.
= 0.85 × 0.70 + 0.70 × 0.30 = 0.595 + 0.21 = 0.805 = 80.5%
Use the CalcHub Grade Calculator's "What-If" tab to run these scenarios without manual math.
When the formula breaks
The formula assumes your professor calculates grades exactly this way. Some professors drop the lowest quiz score, curve the final, or weight categories differently throughout the semester.
Always check your syllabus before trusting any grade calculator — including this one. If your professor uses a custom weighting scheme, plug those exact weights into the Weighted Grade tab instead.
Use it strategically across all your courses
Run the final exam formula for every course you're taking. You'll often find that one class needs nearly a perfect final while another only needs a 65%. That knowledge tells you exactly where to spend the next seven days.
Stack your study hours toward the courses where your grade is most at risk — not toward the subjects you're most comfortable with.