There is no single quarter-grade formula. Your school decides whether the quarter grade comes from that quarter’s assignments — and by which of three methods — or whether the final grade combines quarters with weights, by percent averaging or by letter-point averaging. First find which method your school uses, then the arithmetic is straightforward.
Step 1 — Find your school’s method
Ask two questions. First: are you computing the grade within a quarter, or combining quarters into a semester grade? Second: if within a quarter, does your school use weighted categories, total points, or equal-per-assignment? If combining, does it average percents or letter-points? The same scores give different answers under each method — the proof is in Step 4.
Step 2 — Within a quarter: three methods
Weighted categories. Each category has a fixed percent; the quarter grade is the weighted sum of category averages. Florence One Schools uses Project/Test 45% + Quizzes/Labs 30% + Classwork/Homework 25% per quarter. Worked example: 86 × 45 + 92 × 30 + 78 × 25 = 38.70 + 27.60 + 19.50 = 85.80%.
Total points. Add points earned, divide by points possible; bigger assignments automatically weigh more. Guilford High School’s Chemistry syllabus states it exactly: “if there were 500 points in a marking period and you earned 400 you would receive an 80 or a B for the quarter.” Worked example: 400 / 500 = 80.00%.
Equal per assignment. Every assignment in a category counts equally, whatever its maximum score — Fairfax County’s South County Middle School rule. Worked example: Quiz 9/10 (90%) + Test 60/100 (60%) → (90 + 60) / 2 = 75.00%. Total points on the same scores would give 69 / 110 = 62.73%. The method changes the answer by more than 12 points.
Step 3 — Combining quarters: the weighted formula
Worked example — 40/40/20 (Southwest Virginia Governor’s School, Brunswick, Florence One, CIE). Q1 88 × 40 + Q2 92 × 40 + Exam 76 × 20 = 35.20 + 36.80 + 15.20 = 87.20%.
Worked example — 45/45/10 (Somerset County Public Schools). Q1 88 × 45 + Q2 92 × 45 + Final exam 76 × 10 = 39.60 + 41.40 + 7.60 = 88.60%. Identical scores, different district rule — 1.40 points apart. Weight choice matters more than rounding.
Worked example — 85/15 (Memphis-Shelby, Dallas high school). Quarters averaged: (88 + 92) / 2 = 90.00. Semester = 90.00 × 0.85 + 76 × 0.15 = 76.50 + 11.40 = 87.90%. The same result comes from per-quarter weights of 42.5/42.5/15.
Worked example — Fort Worth ISD six-weeks, sevenths. 1st six-weeks 92, 2nd 85, 3rd 80, semester exam 78: (92 × 2 + 85 × 2 + 80 × 2 + 78 × 1) / 7 = 592 / 7 = 84.57% → 85 as a whole number. Use exact fractions (2/7, 1/7), not the document’s rounded percents (28.5%, 14.5%). Nine-weeks: Q1 88, Q2 92, exam 76 → (88 × 3 + 92 × 3 + 76 × 1) / 7 = 616 / 7 = 88.00% exactly.
Step 4 — Percent average vs letter-point average (the proof)
Prince George’s County Public Schools averages letter grades converted to a 4-point scale (A = 4, B = 3, C = 2, D = 1, E = 0), then maps the average back through its final-grade bands (A = 3.5–4.0, B = 2.5–3.49, C = 1.5–2.49, D = 0.5–1.49, E = 0.0–0.49). Take quarter percents 90, 80, 90, 80 → letters A, B, A, B (PGCPS bands: A 90–100, B 80–89).
- PGCPS method: (4 + 3 + 4 + 3) / 4 = 3.50 → A.
- Percent method: (90 + 80 + 90 + 80) / 4 = 85.00 → B.
Same quarters, different final letter. Never silently convert percents → letters → average, and never silently average percents, without saying which method you are using.
Step 5 — What do I need next quarter?
Rearrange the formula for the remaining quarter — pure algebra, not a school rule. Percent averaging: required = (target × total weight − known contribution) ÷ quarter weight. Example: Q1 88 × 40 + Q2 92 × 40, target 90, exam weight 20 → (90 × 100 − 7,200) / 20 = 90.00%. Letter-point averaging: find the lowest quarter letter whose points reach the target final letter. Example: Q1 90 (A, 4), Q2 80 (B, 3), Q3 90 (A, 4), target final A: need total ≥ 3.5 × 4 = 14 points, have 11, so Q4 needs ≥ 3 points → B, at least 80%. If the required score exceeds 100% (or 4 points), the target is unreachable under those weights.
Rounding — no universal rule
PGCPS rounds gradebook averages to the nearest whole number (82.4 → 82, 91.5 → 92). Fort Worth’s printed example truncates intermediate components (84.5 vs the exact 84.57). Other sources are silent. The calculators on this site show two decimals and round only for display; your school may round differently.
In-progress grades (calculator convention, labelled)
If some quarters are not finished yet, dividing by the weights you entered gives the standing “on completed work so far.” No district source states this normalisation. It is not a predicted final grade and not a school rule.
Why your number may differ from the school’s
- Grade floors. Some schools set a minimum quarter grade; others ban floors entirely.
- Teacher override. Some systems let a teacher replace the computed grade.
- Exam exemptions. Exempt students may have the exam weight dropped or redistributed.
- Retake caps. A retaken test may be capped (for example, at 70 or 90%).
- End-of-course mandates. A state exam may carry a fixed weight regardless of the syllabus.
- IEP modifications. The student’s plan governs over the standard protocol.
- Advanced-course bonus points. Memphis-Shelby adds +5 (AP/Cambridge/IB/CLEP), +4 (dual credit), +3 (honors) percentage points.
Common mistakes
- Averaging percents when your school uses letter-points. Same quarters, different letter — see the proof above.
- Assuming 40/40/20 is universal. Your district may use 45/45/10, 85/15, sevenths, or equal quarters.
- Mixing total-points with equal-per-assignment. A 10-point quiz and a 100-point test count 1:1 in one method and 1:10 in the other.
- Treating a partial standing as the final grade. The in-progress number covers completed work only.
- Assuming one letter scale. Letter cutoffs vary by school — there is no single scale.
- Assuming an exam exists. Some schools have no exam weight; others drop it for exempt or state-tested students.
Calculate it: Quarter Grade Calculator. Midterm: Midterm Grade Calculator. Finals: Final Grade Calculator.