Final Grade Calculator: 2 Quarters?

This calculator works out what you need on your final exam to reach a target grade, using only two quarter grades and the final exam’s weight. You enter your two quarter grades, the exam weight, and your target final grade, and it returns the required exam score. It also shows your current average without the final, so you know where you stand before the exam.

Formula

For a course with two quarters and a final exam, the final grade is a weighted average:

Final Grade = (1 – w/100) × (Q1 + Q2)/2 + (w/100) × Exam

• Q1 – Quarter 1 grade (%, 0–100)
• Q2 – Quarter 2 grade (%, 0–100)
• w – Final exam weight (%, e.g., 20 means the exam is worth 20% of the final grade)
• Exam – Final exam score (%, 0–100)

The calculator solves for Exam given a target final grade. If you want to find the final grade instead, just plug in the exam score. The formula assumes both quarters are equally weighted; if your school weights them differently, adjust accordingly (e.g., Q1 weight 40% and Q2 weight 60% would change the average to 0.4×Q1 + 0.6×Q2).

Worked Example

Using the defaults: Q1 = 85%, Q2 = 90%, exam weight = 20%, target = 90%.

1. Calculate the current average: (85 + 90) / 2 = 87.5%
2. Portion without exam: 1 – 20/100 = 0.8. Weighted contribution: 0.8 × 87.5 = 70%
3. Remaining needed from exam: 90 – 70 = 20%
4. Divide by exam weight: 20 / 0.2 = 100%

So you would need a perfect 100% on the final to reach a 90% overall. The calculator shows 100.00% (rounded to two decimals). If your target were 88%, you would need (88 – 70) / 0.2 = 90%.

How to Use This Calculator

Enter your two quarter grades (as percentages, e.g., 85 for 85%). Then enter the final exam weight – this is the percentage that the final contributes to your overall grade. Common weights are 10–30%, but some courses have a final worth 50% or more. Finally, enter your target final grade (e.g., 90 for an A-). The calculator tells you the minimum score you need on the final to hit that target. If the result is over 100, you cannot reach the target even with a perfect score; if it is below 0, you already have the target locked in.

How to Choose the Right Weight

Check your syllabus or course outline. The weight is usually listed as a percentage. If the final is “20% of your grade,� enter 20. If the course has multiple quarters and a midterm, you may need to combine them into a single “before final� average. For example, if Q1 is 40%, Q2 is 40%, and the final is 20%, you can still use this calculator by treating the “two quarters� as the two 40% components. If you have more than two components, compute a weighted average of all non-final grades and use that as one of the “quarters� (or use a general weighted average calculator).

Common Mistakes and Misconceptions

• Mixing weights and points: Some courses have points, not percentages. Convert to percentages first. If the final is 200 points out of 1000 total, the weight is 20%.
• Ignoring the non-final portion: The formula subtracts the contribution of your current average. A common error is to just average the two quarters and then add the exam weight directly.
• Rounding too early: Do all calculations with full precision, then round only the final answer. Rounding intermediate steps can change the result by a point or two.
• Assuming the final replaces a quarter: Some courses allow the final to replace a low quarter grade. That is a different formula – this calculator assumes the final is an additional component, not a replacement.
• Forgetting that grades are capped at 100: If the required score is 105, you cannot get it. Some teachers curve, but that is not guaranteed.

How to Read the Result

The main output is the required final exam score. If it is, say, 85, you need to score at least 85% on the final to reach your target. If it is 100 or higher, the target is impossible unless you get extra credit. If it is 0 or negative, you have already secured the target regardless of the final. The second output, “Current average,� is the average of your two quarters – useful for understanding your standing. Keep in mind that the calculator assumes the final is the only remaining graded component. If there are other assignments left, they should be included in the “current average� or the weight must be adjusted.

Limitations of the Formula

This formula works for a simple two-quarter-plus-final structure. It does not account for:

• Dropped lowest grades or replacement policies
• Extra credit or curves
• Non-percentage grading scales (e.g., 4.0 GPA)
• Different weights for each quarter

For those cases, you need a more detailed calculator or a manual spreadsheet. Also, the formula assumes the final exam score is on the same 0–100 scale as the quarters. If your final is graded on a different scale (e.g., 50 points), convert it to a percentage first.

Frequently Asked Questions

What if I have three quarters instead of two?

If you have three quarters, you can still use this calculator by combining the first two quarters into one average and treating the third quarter as the “second� input. For example, if Q1=80, Q2=85, Q3=90, enter 82.5 (the average of Q1 and Q2) as the first input and 90 as the second. The result will be the same as a weighted average of all three, as long as the final weight is correct.

Can I use this calculator for a class with only one quarter?

Yes, but you need to adjust. If there is only one quarter grade, enter that same grade for both Q1 and Q2. The current average will be that grade, and the formula will work correctly.

What does “exam weight� mean if the final is worth 200 points?

Convert points to a percentage of total course points. If the course has 1000 total points and the final is 200, the weight is 200/1000 = 20%. Enter 20 in the weight field.

How do I find the final grade if I know my exam score?

Instead of solving for the exam, plug in your expected exam score and solve for the final grade. For example, with Q1=85, Q2=90, weight=20, and exam=95, the final grade is 0.8×87.5 + 0.2×95 = 70 + 19 = 89%. You can use the same formula manually.

Why does the calculator say I need 110%? Is that possible?

No, it means the target is unreachable without extra credit or a curve. For example, if your current average is 80 and the final is worth 20%, even a perfect 100% gives you 0.8×80 + 0.2×100 = 84. So any target above 84 is impossible. The calculator shows the required score, but anything above 100 is not achievable.

Does this calculator work for middle school or high school?

Yes, as long as the grading system uses percentages and a weighted final. Many schools use this structure, but some use points-only or standards-based grading. For standards-based, you would need to convert to percentages first.

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in q1 | Quarter 1 grade | % | 85 | 0
in q2 | Quarter 2 grade | % | 90 | 0
in w | Final exam weight | % | 20 | 0
in target | Target final grade | % | 90 | 0
out req | Required final exam score | % | (target - (1 - w/100) * ((q1 + q2) / 2)) / (w/100) | 2
out cur | Current average (without final) | % | (q1 + q2) / 2 | 2