What do I need on my final? The formula, with worked examples

What do I need on my final? Take the grade you want, subtract your current grade times the share of the class that isn’t the final, and divide what’s left by the final’s weight. As a formula: needed = (target − current × (1 − weight)) ÷ weight, with the weight as a decimal. If you have an 85% now, the final is worth 25%, and you want at least an 80%, you need a 65 on the final. Our free final grade calculator does the sum for you, and the steps below show you how to get the inputs right, which is where most answers go wrong.

Step 1: Find what the final is worth

Open your syllabus and find the grading breakdown. It’s usually a list or table near the top or bottom, like “Homework 20%, Quizzes 15%, Midterm 25%, Final exam 40%.”

• If the final has its own line, that’s your weight.
• If the final is inside a category (“Exams 60%, three exams”), its weight is its share of that category. Three equal exams in a 60% category are worth 20% each.
• If the class uses points instead of percentages (“the final is 200 of 1,000 points”), the weight is its points over the total: 200 ÷ 1,000 = 20%.

Step 2: Work out your current grade on everything else

Your “current grade” here means your average on everything that isn’t the final, weighted the way the syllabus weights it.

1. List every category except the final, with its weight.
2. Find your average in each category. Drop the lowest score first if your syllabus drops one.
3. Multiply each average by its weight, add them up, and divide by the total weight of those categories.

The grade on your course site might already be this number. It might not be: some course sites skip ungraded work, count it as zero, or don’t apply the syllabus weights. Our guide to what-if grades, and when they’re wrong shows how to tell. Our weighted grade calculator can do this step from your category averages.

Step 3: Pick your target from the syllabus scale

Use the cutoff your syllabus actually gives. Many classes use A 90, B 80, C 70, D 60, but plenty don’t: a B+ might start at 87, or an A at 93. If the syllabus says scores round up (89.5 becomes 90), you can use the rounded cutoff. If it says nothing, don’t assume it.

Step 4: Solve “what do I need on my final?” and read the answer

Put the three numbers into the formula, or into the calculator.

• Between 0 and 100: that’s the score you need.
• Over 100: that grade isn’t reachable on the final alone. Look at the next grade down.
• Below 0: you’d keep that grade even with a zero, by the numbers. Read the syllabus anyway for any rule that you must take or pass the final.

Worked example 1: everything else is graded

You have an 85% on everything so far, and the final is worth 25%. The other 75% of the class is done.

Your 85% on 75% of the class is worth 85 × 0.75 = 63.75 points of your final grade. The final can add up to 25 more.

Grade you want	Sum	You need on the final
A (90)	(90 − 63.75) ÷ 0.25	105%
B (80)	(80 − 63.75) ÷ 0.25	65%
C (70)	(70 − 63.75) ÷ 0.25	25%
D (60)	(60 − 63.75) ÷ 0.25	−15% (already safe)

So an A is out of reach without extra credit, and a B needs a 65. Even with rounding to 89.5, the A would still need a 103. That’s useful to know a month out: it tells you to protect the B rather than chase the A.

Worked example 2: some work still isn’t graded

Often a project or the last homework is still open when you start planning for the final. The formula above treats your current grade as final, so here it’s easier to count points.

The syllabus says: Homework 25%, Midterm 25%, Project 20%, Final 30%. Your homework average is 90, your midterm was a 76, and the project isn’t graded yet. You expect about an 85 on it. You want an 80 in the class.

Each category gives you its weight times your score:

• Homework: 25 × 0.90 = 22.5
• Midterm: 25 × 0.76 = 19.0
• Project (estimate): 20 × 0.85 = 17.0

That’s 58.5 points. You need 80, so the final has to supply 80 − 58.5 = 21.5 of its 30 points. 21.5 ÷ 30 = 71.7% on the final.

If the project comes back at a 75 instead, it gives you 15 points, your total before the final is 56.5, and the final needs 23.5 of 30, or 78.3%. That’s why it’s worth redoing the sum once every grade is in.

(The two methods agree. In this example your average on the non-final 70% of the class is 58.5 ÷ 70 = 83.57%, and (80 − 83.57 × 0.7) ÷ 0.3 gives the same 71.7%.)

Worked example 3: a class graded by points

The class has 1,000 points in total. The final is worth 200 of them. You’ve earned 680 of the 800 points so far, which is 85%.

• For a 90% (900 points), you’d need 900 − 680 = 220 of 200. Not reachable.
• For an 80% (800 points), you need 800 − 680 = 120 of 200, which is 60%.

The formula gives the same: a weight of 20%, a current grade of 85, and (80 − 85 × 0.8) ÷ 0.2 = 60.

When the simple answer is wrong

The formula is exact for the inputs you give it. These are the cases where the inputs need care:

• The final replaces your lowest exam. A good final then counts twice: once as the final, and once in place of a weak midterm. Work it out by category, as in example 2, with the replaced score swapped for your final score.
• Dropped grades. If the lowest quiz is dropped, drop it before you average the category, or your current grade comes out too low.
• A must-pass rule. Some syllabi say you must pass the final to pass the class, or must take it at all. No average overrides that.
• Curves and extra credit. Neither is guaranteed until the professor says so. Plan on the scale as written.
• Your current grade isn’t what you think. If your course site’s total leaves things out or skips the syllabus weights, every answer built on it is off. Check it by hand once.

If you’re not sure how your class handles any of these, ask your professor or check the syllabus’s grading section. It’s a normal question near the end of term.

Where Coursebird fits

Coursebird does this sum for every class at once. It reads your grades from your school’s course site, takes the weights and dropped grades from your syllabus, and shows what you need on each final to keep or reach each grade. The syllabus facts it uses (weights, drop rules, the grading scale) each show the line they came from, so you can check them.

Coursebird is free and in beta, and you can join the list from this page. Until then, the final grade calculator works without an account, and nothing you type is saved. When you know what you need, our guide to building a finals study schedule from your syllabi helps you spend your time where it counts. See how Coursebird shows your grades.