Grade Calculator

Work out your final course grade from weighted assignments, or your percentage and letter grade for a single test. Enter your scores, and the calculator updates as you type. It runs entirely in your browser: free, instant, no sign-in.

How the grade calculator works

There are two modes. Weighted course grade combines several assignments, each with its own weight: final grade = (score × weight) added up for every assignment, divided by 100. For example, a 90 on homework worth 40% and an 80 on the final exam worth 60% gives (90 × 40 + 80 × 60) ÷ 100 = (3,600 + 4,800) ÷ 100 = 84%, which is a B. The weights must add up to 100% — if they do not, the calculator tells you the total so you can fix it. Test score is simpler: percentage = score earned ÷ total possible × 100. A score of 45 out of 50 is 45 ÷ 50 × 100 = 90%, which is an A.

The letter grade uses the standard US scale: A = 90–100%, B = 80–89%, C = 70–79%, D = 60–69%, and F = below 60%. Percentages are rounded to two decimal places.

Your final grade is rarely a simple average. Most courses weight their assignments — homework might count for 40% and the final exam for 60% — so a high score on a small assignment and a low score on a big exam do not cancel each other out. The Grade Calculator does that weighted maths for you: enter each assignment’s score and its weight, and it shows your final percentage and your letter grade. It also works as a test calculator: enter the score you earned and the total possible, and it gives the percentage and the letter grade for that single test. It updates as you type, runs entirely in your browser, and needs no sign-in.

The letter grade uses the standard US scale, which is the scale used by most schools and colleges in the United States: A = 90–100%, B = 80–89%, C = 70–79%, D = 60–69%, and F = below 60%. Some schools use plus and minus grades (A−, B+), but this calculator uses the plain letter scale, which is the most widely used version. If your school uses a different scale, the percentage the calculator shows is still exact — only the letter attached to it may differ.

How to use the calculator, step by step

There are two modes. Pick the one that matches what you are working out.

• Step 1 — Pick a mode. “Weighted course grade” combines several assignments into one final grade. “Test score” works out the percentage and letter grade for a single test or quiz.
• Step 2 (weighted mode) — Enter each assignment. For every assignment, type its score (0 to 100) and its weight as a percentage. Add more assignments with the “+ Add assignment” button, and remove any row with its Remove button. The weights must add up to 100% — if they do not, the calculator shows the total so you can fix it.
• Step 2 (test mode) — Enter the two numbers. Type the score you earned and the total possible score — for example, 45 earned out of 50 possible.
• Step 3 — Read the result. The big letter and percentage are your grade. Under them, the calculator shows the working — for the weighted mode, that your weights total 100% — and a reminder of the grade scale.
• Step 4 — Clear to start again. The Clear button empties all the inputs and leaves one blank assignment row ready for the next calculation.

How the maths works

Two formulas sit behind the calculator:

• Weighted grade = (score × weight) added up for every assignment, divided by 100. Each assignment contributes its score multiplied by its weight, and the contributions are added together. Because the weights add up to 100, dividing by 100 gives the final percentage. Example: a 90 on homework worth 40% and an 80 on the final exam worth 60% gives (90 × 40 + 80 × 60) ÷ 100 = (3,600 + 4,800) ÷ 100 = 84%. That is a B.
• Test percentage = score earned ÷ total possible × 100. Example: 45 out of 50 is 45 ÷ 50 × 100 = 90%, which is an A. Another example: 17 out of 20 is 17 ÷ 20 × 100 = 85%, which is a B.

The letter grade comes from the standard US scale: A = 90–100%, B = 80–89%, C = 70–79%, D = 60–69%, F = below 60%. Percentages are rounded to two decimal places, so a result of 89.995% shows as 90% and earns an A, while 89.99% stays a B. The boundary is exact: 90 is an A, 89.99 is a B, 60 is a D, and 59.99 is an F.

The table below shows the grade scale at a glance:

• A — 90% to 100%
• B — 80% to 89%
• C — 70% to 79%
• D — 60% to 69%
• F — below 60%

Worked examples

Example 1 — Weighted grade: 90 (weight 40) + 80 (weight 60). Multiply each score by its weight: 90 × 40 = 3,600 and 80 × 60 = 4,800. Add them: 3,600 + 4,800 = 8,400. Divide by 100: 8,400 ÷ 100 = 84%. The weights total 40 + 60 = 100%, so the result is valid, and 84% is a B.

Example 2 — Test score: 45 out of 50. Divide the score by the total: 45 ÷ 50 = 0.9. Multiply by 100: 0.9 × 100 = 90%. That is an A.

Example 3 — Test score: 17 out of 20. Divide the score by the total: 17 ÷ 20 = 0.85. Multiply by 100: 0.85 × 100 = 85%. That is a B.

Example 4 — Weighted grade with three assignments: homework 85 (weight 20), midterm 78 (weight 30), final exam 92 (weight 50). Multiply: 85 × 20 = 1,700, 78 × 30 = 2,340, and 92 × 50 = 4,600. Add them: 1,700 + 2,340 + 4,600 = 8,640. Divide by 100: 8,640 ÷ 100 = 86.4%. The weights total 20 + 30 + 50 = 100%, so the result is valid, and 86.4% is a B.

Example 5 — Test score: 0 out of 40. Divide the score by the total: 0 ÷ 40 = 0. Multiply by 100: 0 × 100 = 0%. That is an F. A zero is still a valid score — the calculator only rejects a total of zero, because dividing by zero has no answer.

Example 6 — What score do you need on the final? Suppose homework (weight 40) is already done at 88, and the final exam (weight 60) is still to come, and you want an overall 90 (an A). The homework contributes 88 × 40 ÷ 100 = 35.2 points. You need 90 − 35.2 = 54.8 points from the final, and the final is worth 60 points, so the score you need is 54.8 ÷ 60 × 100 = 91.33%. Try the numbers in the calculator: 88 at weight 40 and 91.33 at weight 60 gives 90% — an A.

Common mistakes

• Weights that do not add up to 100%. The most common error is entering weights like 40 and 50, which add up to 90%, and wondering why the result looks wrong. Weights are shares of the final grade, so they must total 100%. The calculator shows the actual total — for example, “Weights add up to 85%, not 100%” — so you can see exactly how far off you are.
• Averaging the scores instead of weighting them. A simple average of 90 and 80 is 85, but the weighted grade with weights 40 and 60 is 84 — the lower score counts more because its weight is bigger. When the weights are unequal, the simple average is the wrong answer.
• Entering the weight as a decimal instead of a percentage. A weight of 40% goes in as 40, not 0.4. If you enter 0.4, the weights will add up to far less than 100% and the calculator will flag it.
• Mixing up the score and the total on a test. The score you earned goes first and the total possible goes second: 45 out of 50, not 50 out of 45. Entering them the wrong way round gives a percentage over 100%, which the calculator rejects with a clear error.
• Assuming a 90 is always an A. The plain A starts at 90% on the standard US scale used here, but some schools use plus and minus grades, where 90–92 might be an A−, or set the A boundary at 93. The percentage is exact either way; check your school’s own scale if the letter matters for your record.

Related tools

The grade calculator sits in the Math Tools group, and two companion tools cover the rest of everyday percentage maths.

• Percentage Calculator — work out any percentage, percentage increase or decrease, or what percentage one number is of another.
• Tip Calculator — work out the tip, the total bill and each person’s share when splitting a bill.

For all of ToolZana’s free tools, start at the ToolZana home page.

Tips for keeping your grade up

• Know the weights before the course starts. The syllabus lists every assignment’s weight. Enter them in the calculator at the start of term, and you always know what each remaining assignment is worth.
• Work out what you need on the final. Once some assignments are done, enter their real scores and try different scores for the final exam until the result hits the grade you want — that is the target to aim for.
• Do not ignore a small assignment. A 10% assignment still moves the final grade by up to 10 points — the difference between a B and an A. Enter it and see the effect before skipping it.
• Check the weights add up to 100%. If a syllabus lists weights that total 95% or 105%, ask the teacher — it usually means an assignment is missing from the list or a weight was printed wrong.
• Track your grade through the term. Recalculate after every graded assignment comes back. A small drop early in the term is easy to fix; the same drop found out in the last week is not.

The short version

The Grade Calculator works out a weighted course grade as (score × weight) added up for every assignment, divided by 100 — the weights must total 100% — and a test score as score earned ÷ total possible × 100. A 90 worth 40% and an 80 worth 60% gives 84%, a B. A test score of 45 out of 50 is 90%, an A, and 17 out of 20 is 85%, a B. The letter grade uses the standard US scale: A 90–100%, B 80–89%, C 70–79%, D 60–69%, F below 60%. The tool is free, runs entirely in your browser, and needs no sign-in.

Frequently Asked Questions

What is a grade calculator?

A grade calculator works out your final percentage and letter grade. In weighted mode it combines several assignments — each with a score and a weight — into one final course grade. In test mode it turns a single score, like 45 out of 50, into a percentage and a letter grade. The ToolZana grade calculator does both, updates as you type, and uses the standard US scale: A 90–100%, B 80–89%, C 70–79%, D 60–69%, F below 60%.

How do I calculate my weighted grade?

Multiply each assignment’s score by its weight, add all the results together, and divide by 100. For example, a 90 worth 40% and an 80 worth 60% gives (90 × 40 + 80 × 60) ÷ 100 = (3,600 + 4,800) ÷ 100 = 84%, which is a B. The weights must add up to 100% — if they do not, the calculator shows the actual total so you can fix it. Enter your scores and weights in the calculator and it does the whole calculation for you.

How do I calculate a test score as a percentage?

Divide the score you earned by the total possible score, then multiply by 100. A score of 45 out of 50 is 45 ÷ 50 × 100 = 90%, which is an A. A score of 17 out of 20 is 17 ÷ 20 × 100 = 85%, which is a B. Use the “Test score” mode in the calculator: enter the score earned and the total possible, and it shows the percentage and the letter grade straight away.

What weights should I use for my assignments?

Use the weights from your course syllabus — that is the document that says how much each assignment counts toward the final grade. A typical split is homework 20%, midterm 30% and final exam 50%, but every course is different. The weights must add up to 100%: if your syllabus lists weights that total 95% or 105%, an assignment is probably missing from the list or a weight was printed wrong, so check with your teacher.

Why do my weights have to add up to 100%?

Weights are shares of the final grade, so together they must make up the whole grade — 100%. If the weights add up to 85%, that means 15% of the grade is unaccounted for, and the calculator cannot know what that missing 15% is worth. The calculator checks the total and shows a clear message, such as “Weights add up to 85%, not 100%”, so you can correct the weights before trusting the result.

What score do I need on the final exam to get an A?

Work out what your finished assignments already contribute, subtract that from 90, and divide by the final exam’s weight. For example, if homework worth 40% is done at 88, it contributes 88 × 40 ÷ 100 = 35.2 points. You need 90 − 35.2 = 54.8 points from the final, which is worth 60 points, so the score you need is 54.8 ÷ 60 × 100 = 91.33%. Enter your real scores in the calculator and try different final-exam scores until the result reaches 90%.

What is the grade scale used by the calculator?

The calculator uses the standard US letter-grade scale: A = 90–100%, B = 80–89%, C = 70–79%, D = 60–69%, and F = below 60%. The boundaries are exact: 90 is an A and 89.99 is a B; 60 is a D and 59.99 is an F. Some schools use plus and minus grades (A−, B+) or set the A boundary at 93 instead of 90. The percentage the calculator shows is exact under any scale — only the letter attached to it may differ, so check your school’s own scale if the letter matters for your record.

How do I calculate my grade if my teacher uses points instead of percentages?

Add up all the points you earned and divide by all the points possible, then multiply by 100. For example, if you earned 342 points out of 400 possible, your percentage is 342 ÷ 400 × 100 = 85.5%, which is a B. That is exactly what the calculator’s test mode does: enter 342 as the score earned and 400 as the total possible. If each assignment is worth a different number of points, the points system is already weighting them for you — bigger assignments count more because they have more points.

Can I use this calculator for a GPA?

Not directly. This calculator gives you a percentage and a letter grade for one course or one test. A GPA combines the letter grades of several courses, usually by turning each letter into points (A = 4, B = 3, C = 2, D = 1, F = 0) and averaging them, sometimes weighted by credit hours. Use this calculator to find each course’s letter grade first, then convert those letters to GPA points and average them.

What happens if I enter a score above 100?

The calculator rejects it with an error, because scores in this tool are percentages from 0 to 100. A score of 105 on a test usually means the test had extra credit, so the total possible was more than 100 — for example, 105 out of 110. Enter the score and the total in test mode instead: 105 ÷ 110 × 100 = 95.45%, which is an A. In weighted mode, convert the score to a percentage first, then enter that percentage.

Does the grade calculator work for any subject?

Yes. The maths is the same for every subject — a weighted average of scores, or a score divided by a total — so the calculator works for maths, science, history, languages and any other course. It does not store your scores, does not need a sign-in, and works entirely in your browser, so you can use it for as many courses as you like.

Is the grade calculator free?

Yes — the Grade Calculator is completely free, with no sign-in and no limits. It runs entirely in your browser, so nothing you enter is uploaded anywhere, and you can use it as often as you like, for as many assignments, courses and tests as you need.