How this calculator works

Four modes. Four formulas. Nothing hidden.

Everything runs in your browser. Your grades are never sent anywhere, and nothing is stored between visits.

01 — Test score

You enter points earned and total points. The calculator returns a percentage and a letter.

percentage = points earned ÷ total points × 100

Worked example. 43 points out of 50 gives 86%, letter B on the default scale.

Limits: total points must be greater than 0 and no more than 1,000,000. Points earned must be between 0 and the total. Decimals are allowed for half marks.

02 — Weighted grade

Each component has a grade in percent and a weight in percent. The weights must total exactly 100%.

final percentage = sum of (grade × weight ÷ 100)

Worked example. Homework 92% at 15%, quizzes 78% at 20%, midterm 85% at 25%, final exam 88% at 40%.

The calculator shows 85.85%, letter B.

If your weights do not total 100%, you get no number. You get a message naming the total you entered, such as "Weights total 65%. Adjust them to 100% to calculate a final grade." That is deliberate: a weighted average over weights that do not sum to 100% is not a grade. What to do when your weights do not add up covers the two fixes.

03 — Final exam

You enter your current grade, the grade you want for the course, and how much the final exam is worth. Your current grade must cover everything except the final.

required = (target − current × (1 − exam weight ÷ 100)) ÷ (exam weight ÷ 100)

Worked example. Current grade 83%, target 85%, exam worth 30%.

required = (85 − 83 × 0.70) ÷ 0.30
         = (85 − 58.10) ÷ 0.30
         = 26.90 ÷ 0.30
         = 89.6666…

The calculator shows 89.67% and tells you to aim for at least 89.67%.

Three outcomes are possible:

• More than 0, up to 100. Reachable. With current 83%, target 80% and a 30% exam, you need 73%.
• Above 100%. Not reachable on the exam alone. With current 83%, target 90% and a 30% exam, the answer is 106.33%.
• Zero or below. Already secured under this formula. With current 95%, target 60% and a 20% exam, the answer is −80%, and the calculator says the target is secured.

This mode uses no letter scale. It works in percentages only, because the thing you need is a percentage.

04 — Teacher table

You enter the total points on a test. The calculator prints one row per whole point, from full marks down to zero, using your scale.

each row: percentage = points earned ÷ total points × 100
rows = total points + 1

Worked example. A 25-point test gives 26 rows, because zero is a score too.

Limits: 1 to 500 points, whole numbers only. A fractional total is refused, because a table in half-point steps is a different table.

When you print, only the table prints. The input panels are hidden, and your scale is printed under the heading.

The grading scale

The default scale is A ≥ 90, B ≥ 80, C ≥ 70, D ≥ 60, F ≥ 0.

That default is ours, not a standard. Real scales differ, and they differ at exactly the point that matters. SUNY Broome Community College policy AA4010 sets A at 93–100 and A− at 90–92. The Lincoln Memorial University PA program catalog sets A at 90.00–100%. A score of 91% is an A at one and an A− at the other.

So open Customize the grading scale and enter your own. Rules: 2 to 12 rows, unique labels of 1 to 12 characters, thresholds ordered highest to lowest, and the last row must start at 0. A pass/fail scale is two rows: Pass at 70 and Fail at 0.

Your scale applies to the test score, the weighted grade and the teacher table. It is not saved; it resets when you reload the page.

Rounding, exactly

This is where calculators quietly disagree with each other, so here is our rule in full.

• Percentages are displayed to two decimal places. 89.6666… is shown as 89.67.
• Letters are chosen from the undisplayed, unrounded percentage.

That matters at a boundary. 44.75 out of 50 is exactly 89.5%. Displayed, it is 89.5%. The letter is B, not A, because 89.5 is below the A threshold of 90. The calculator does not round 89.5 up to 90 and then hand you an A.

Your school may round differently, and may round before assigning a letter. Ours does not. Check your school's rules.

What this calculator will not do

• It does not know your course, your syllabus or your teacher's rounding.
• It does not drop your lowest score, add extra credit, or apply a curve. You can model those yourself; see why your number can differ from your gradebook.
• It does not produce an official grade. Only your school does that. See the disclaimer.

Sources

• Default scale, formulas, limits and rounding: read from the calculator's own code in this repository (public/assets/calculations.js, public/assets/app.js) and re-tested in a browser on 16 October 2026. Every number on this page was produced by the calculator, not by hand.
• SUNY Broome Community College, Grading Scale Policy AA4010, approved 25 May 2023. Checked 16 October 2026.
• Lincoln Memorial University, Master of Medical Science PA Program (Knoxville) catalog, Grading System. Checked 16 October 2026.