Grade Calculator: Weighted Average, Letter Grade & Final

What does 84.30 mean?

It means 85, 92 and 78 with weights 30, 30 and 40 average 84.30 — a B. The weights pull the average toward the heaviest assignment: the 78 counts for 40% of the grade, so it drags the average down more than the 92 lifts it up. The weighted average, the letter grade and the points needed on the final are three outputs, never the same number — the average is the number, the letter is what the number is called, and the points needed are what the final exam has to do.

Three things to check before you trust the number

The weights are what matters, not the scores. The same three scores average 85.00 with weights 50/25/25 and 84.30 with weights 30/30/40 — the weighting decides the grade, not the scores alone. Check the weights against your syllabus before you trust the average.

A zero is the most expensive score. A 0 on the first assignment drops the average from 84.30 to 58.80 — 25.50 points on one assignment. A low score on a heavy assignment costs more than the same score on a light one, and the calculator shows you exactly how much.

Above 100% on the final means the target is gone. At a 30% final weight, a 90% target needs 103.30% on the final — more than a perfect score. The calculator says so plainly instead of giving you a number you cannot reach.

Worked example

On the defaults: 85, 92 and 78 with weights 30, 30 and 40, final weight 30%, target 85%.

1. Multiply each score by its weight: 85 × 30 = 2,550; 92 × 30 = 2,760; 78 × 40 = 3,120.
2. Add the products: 2,550 + 2,760 + 3,120 = 8,430.
3. Add the weights: 30 + 30 + 40 = 100.
4. Divide: 8,430 ÷ 100 = 84.30.
5. Letter grade: 84.30 sits between 83 and 87, so it is a B.
6. Points needed on the final: (85 − 84.30 × 0.70) ÷ 0.30 = (85 − 59.01) ÷ 0.30 = 25.99 ÷ 0.30 = 86.63% (unrounded 86.633333).
7. Smallest score on assignment 3 for an average of at least 90: 93 — at 93 the average is 90.30, and at 92 it is 89.90, a B+.
8. Smallest final-exam weight for a 90% target to be reachable: 37% — at 37% the points needed are 99.71 (unrounded 99.705405), and at 36% they are 100.13.

Every branch, checked

• All 90s: All 90s: Weighted average 90.00 (A-); you need 73.33% on the final to reach 85.00%. All 90s — average 90.00, an A-, and only 73.33% on the final is needed for 85%.
• All 70s: All 70s: Weighted average 70.00 (C-); you need 120.00% on the final to reach 85.00%. All 70s — average 70.00, a C-, and 120.00% on the final is needed for 85% — out of reach.
• Weights 50/25/25: Weights 50/25/25: Weighted average 85.00 (B); you need 85.00% on the final to reach 85.00%. The same scores, a different weighting — average 85.00, a B.
• All 100s: All 100s: Weighted average 100.00 (A+); you need 50.00% on the final to reach 85.00%. All 100s — average 100.00, an A+, and only 50.00% on the final is needed for 85%.
• 60/55/62: 60/55/62: Weighted average 59.30 (F); you need 144.97% on the final to reach 85.00%. 60/55/62 — average 59.30, an F, and 144.97% on the final is needed for 85% — out of reach.
• Final weight 40%, target 90%: Final weight 40%, target 90%: Weighted average 84.30 (B); you need 98.55% on the final to reach 90.00%. A heavier final and a higher target — 98.55% on the final is needed, nearly perfect.
• Final weight 20%, target 85%: Final weight 20%, target 85%: Weighted average 84.30 (B); you need 87.80% on the final to reach 85.00%. A lighter final is less forgiving — 87.80% on the final is needed for 85%.
• Final weight 30%, target 90%: Final weight 30%, target 90%: Weighted average 84.30 (B); you need 103.30% on the final to reach 90.00%. A 90% target at a 30% final weight — 103.30% on the final is needed, out of reach.
• 95/88/91, weights 25/25/50: 95/88/91, weights 25/25/50: Weighted average 91.25 (A-); you need 70.42% on the final to reach 85.00%. 95/88/91 with the last assignment worth half — average 91.25, an A-, and 70.42% on the final is needed for 85%.
• 80/85/75, weights 20/30/50: 80/85/75, weights 20/30/50: Weighted average 79.00 (C+); you need 99.00% on the final to reach 85.00%. 80/85/75 with the last assignment worth half — average 79.00, a C+, and 99.00% on the final is needed for 85%.

The reverses, worked backwards

• Smallest score on assignment 3 for the average to REACH at least 90: 93 — at 93 the figures are Weighted average 90.30 (unrounded 90.300000) (A-); you need 72.63% (unrounded 72.633333) on the final to reach 85.00%; at the lower neighbor the figures are Weighted average 89.90 (unrounded 89.900000) (B+); you need 73.57% (unrounded 73.566667) on the final to reach 85.00%; at the upper neighbor the figures are Weighted average 90.70 (unrounded 90.700000) (A-); you need 71.70% (unrounded 71.700000) on the final to reach 85.00% — verdict: STEP.
• Smallest score on assignment 1 for the average to REACH at least 85: 88 — at 88 the figures are Weighted average 85.20 (unrounded 85.200000) (B); you need 84.53% (unrounded 84.533333) on the final to reach 85.00%; at the lower neighbor the figures are Weighted average 84.90 (unrounded 84.900000) (B); you need 85.23% (unrounded 85.233333) on the final to reach 85.00%; at the upper neighbor the figures are Weighted average 85.50 (unrounded 85.500000) (B); you need 83.83% (unrounded 83.833333) on the final to reach 85.00% — verdict: STEP.
• Smallest final-exam weight for a 90% target to be reachable: 37% — at 37% the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 99.71% (unrounded 99.705405) on the final to reach 90.00%; at the lower neighbor the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 100.13% (unrounded 100.133333) on the final to reach 90.00%; at the upper neighbor the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 99.30% (unrounded 99.300000) on the final to reach 90.00% — verdict: STEP.
• Largest target grade reachable with 100% on the final (final weight 30%): 89% — at 89% the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 99.97% (unrounded 99.966667) on the final to reach 89.00%; at the lower neighbor the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 103.30% (unrounded 103.300000) on the final to reach 90.00%; at the upper neighbor the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 96.63% (unrounded 96.633333) on the final to reach 88.00% — verdict: STEP.
• Smallest score on assignment 2 for the average to REACH at least 80: 78 — at 78 the figures are Weighted average 80.10 (unrounded 80.100000) (B-); you need 96.43% (unrounded 96.433333) on the final to reach 85.00%; at the lower neighbor the figures are Weighted average 79.80 (unrounded 79.800000) (C+); you need 97.13% (unrounded 97.133333) on the final to reach 85.00%; at the upper neighbor the figures are Weighted average 80.40 (unrounded 80.400000) (B-); you need 95.73% (unrounded 95.733333) on the final to reach 85.00% — verdict: STEP.
• Largest score on assignment 3 for the average to STAY at or below 85: 79 — at 79 the figures are Weighted average 84.70 (unrounded 84.700000) (B); you need 85.70% (unrounded 85.700000) on the final to reach 85.00%; at the lower neighbor the figures are Weighted average 85.10 (unrounded 85.100000) (B); you need 84.77% (unrounded 84.766667) on the final to reach 85.00%; at the upper neighbor the figures are Weighted average 84.30 (unrounded 84.300000) (B); you need 86.63% (unrounded 86.633333) on the final to reach 85.00% — verdict: STEP.

What the defaults assume

The defaults are 85, 92 and 78 with weights 30, 30 and 40, a 30% final exam and an 85% target — three assignments and one final, on a 0 to 100 scale with the usual letter bands. They are a starting point, not a benchmark: your course may have more assignments, different weights, or a different letter scale, and the right grade for you is the one your syllabus describes. Change the eight numbers to your own and the calculator recomputes instantly. The weights are what matters, not the scores — check them against your syllabus before you trust the average.

These notes repeat in every explainer section because this page is built to be read start to finish: the defaults are one student’s grades, not a standard; the weights are what matters, not the scores; a zero is the most expensive score; and above 100% on the final means the target is gone.

Output · formula · meaning

Who uses this

• A student who wants to know what their grade is right now — 84.30, a B — and what they need on the final for an A.
• A student with a zero who wants to know exactly how much it cost — 25.50 points on the average — and what it takes to recover.
• A teacher who checks a student’s weighted average against the syllabus weights in seconds.
• A parent who wants the number behind the report card, not just the letter.

Accuracy & limitations

The calculator does the arithmetic exactly — the weighted average is the sum of score times weight divided by the sum of the weights, the letter comes from the standard bands, and the points needed on the final come from the target, the average and the final weight — and every figure on this page is checked against an independent model. What it cannot do is read your syllabus: letter bands vary by school (some use A from 90, some from 93), some courses drop the lowest score, and some weight the final differently. It also takes three assignments — a course with more assignments needs the weighted-grade-calculator page, which takes the coursework as a whole. And the average is 84.83 unrounded 84.825000 on fractional scores — the page prints the unrounded figure so the rounding does not mislead you.

Cite this calculator

Weighted average = (score 1 × weight 1 + score 2 × weight 2 + score 3 × weight 3) / (weight 1 + weight 2 + weight 3); points needed on the final = (target − weighted average × (1 − final weight)) / final weight. On the defaults — 85, 92 and 78 with weights 30, 30 and 40, final weight 30%, target 85% — the weighted average is 84.30, a B, and the points needed on the final are 86.63%. Smallest score on assignment 3 for an average of at least 90: 93. Smallest score on assignment 1 for an average of at least 85: 88. Smallest final-exam weight for a 90% target to be reachable: 37%. Largest target grade reachable with 100% on the final (final weight 30%): 89%. Smallest score on assignment 2 for an average of at least 80: 78. Largest score on assignment 3 for an average of at or below 85: 79. Source: Bright Side Kit, brightoolbox.com.

Frequently asked questions