Quick Answer

A student with an 85% current grade who wants a 90% in a course where the final is worth 30% needs to score 101.67% on the final, which is not achievable.

Current Grade (%)

Final Exam Weight (%)

Desired Grade (%)

Common Examples

Input	Result
Current: 85%, Final weight: 40%, Desired: 90%	Needed: 97.50% (achievable but challenging)
Current: 90%, Final weight: 30%, Desired: 90%	Needed: 90.00%
Current: 75%, Final weight: 25%, Desired: 80%	Needed: 95.00%
Current: 92%, Final weight: 20%, Desired: 90%	Needed: 82.00%
Current: 80%, Final weight: 50%, Desired: 85%	Needed: 90.00%

How It Works

The Formula

Needed Final Grade = (Desired Grade - Current Grade x (1 - Final Weight / 100)) / (Final Weight / 100)

This formula works by treating the course grade as a weighted average of two components: the work completed so far (weighted at 1 - final weight) and the final exam (weighted at the final weight).

Rearranging the weighted average:

Course Grade = Current Grade x (1 - w) + Final Grade x w

Where w = Final Weight / 100. Solving for the Final Grade:

Final Grade = (Course Grade - Current Grade x (1 - w)) / w

The result tells you the exact percentage you need to earn on the final exam. If the result exceeds 100%, the desired grade is not achievable through the final exam alone. If the result is below 0%, you have already secured the desired grade regardless of your final exam performance.

Worked Example

A student has an 85% current grade. The final exam is worth 40% of the course grade. The student wants to finish with a 90%.

w = 40 / 100 = 0.40

Needed = (90 - 85 x (1 - 0.40)) / 0.40

Needed = (90 - 85 x 0.60) / 0.40

Needed = (90 - 51) / 0.40

Needed = 39 / 0.40

Needed = 97.50%

The student needs to score 97.50% on the final to reach an overall grade of 90%. This is a high target but still within the possible range.

Understanding the Impact of Final Exam Weight

The weight of the final exam determines how much influence it has on the overall grade. A final worth 50% of the course has a much larger effect than one worth 10%. When the final carries a heavy weight, even a moderate gap between the current and desired grades may be achievable. When the final carries a small weight, even a small gap may require a very high score.

Related Calculators

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Frequently Asked Questions

How is this formula derived?

The course grade is a weighted average: Course Grade = (Current Grade x Non-Final Weight) + (Final Grade x Final Weight). Solving this equation for Final Grade produces the formula used in this calculator. The non-final weight is simply 1 minus the final weight expressed as a decimal.

What does it mean if the needed grade is over 100%?

If the calculator shows a needed grade above 100%, it means the desired course grade is not achievable through the final exam alone. You would need to explore other options, such as extra credit (if available) or adjusting your target grade to something more realistic given your current standing.

What if the needed grade is negative?

A negative needed grade means you have already secured your desired course grade. Even scoring 0% on the final exam would still result in a course grade at or above your target. This typically happens when your current grade is well above your desired grade and the final exam weight is relatively small.

Does this work for weighted categories other than a final exam?

Yes. The formula works for any scenario where you know your current grade on a portion of the course and want to find the grade needed on the remaining portion. For example, if homework is worth 60% and you have a 92% on homework, you can calculate what you need on the remaining 40% (tests, projects, etc.).

How do I find my current grade and the final exam weight?

Your current grade is typically available in your school's online grade portal or learning management system. The final exam weight should be listed in the course syllabus. Common final exam weights range from 15% to 40%, depending on the course and institution.

Learn More

GPA and Grades: Everything Students Need to Know

How GPA is calculated on the 4.0 scale, how to compute semester and cumulative GPA, and strategies for raising your GPA. Step-by-step examples included.