Every calculator here states the convention it used, because grading conventions are where calculators disagree — far more often than the arithmetic. This page collects those conventions in one place. If a number on this site surprises you, the explanation is almost certainly below.
Rounding
Percentages are rounded to one decimal place, GPAs to two, and rounding is half-up, away from zero: 83.65% displays as 83.7%, and a trailing zero is dropped, so 85.0% displays as 85%.
Half-up is not the only defensible rule — the alternative, half-to-even or “banker's rounding”, is what Python and several spreadsheet functions do by default, and it would show 83.65% as 83.6%. We chose half-up because it is what a US gradebook does and what a student expects when a teacher says a grade “rounds up”. The consequence to know about is that a displayed figure is not the figure we calculated with: every intermediate value is kept at full precision and rounded only for display. A course grade of 89.95% shows as 90% but is still below a 90% cut-off, and the letter shown next to it will say so. That is deliberate, and it is the single most common way a calculator misleads someone: rounding the percentage first and then reading the letter off the rounded number promotes a grade the school would not.
One further detail, because it changes answers at the boundary. Binary floating point cannot hold 0.1 exactly, so a calculation whose true answer is exactly 64 can arrive as 63.99999999999999. Where a comparison decides whether a target is reachable, we compare with a tolerance of 1×10−9 rather than exactly. Without it, a required final-exam score of precisely 100% would read as impossible about half the time.
Percentage to letter grade
Unless a page says otherwise, letters come from the standard US plus/minus scale. A percentage lands in a band when it is greater than or equal to the band's floor:
| Letter | Percentage | Grade points (4.0) |
|---|---|---|
| A+ | 97–100 | 4.0 |
| A | 93–96 | 4.0 |
| A− | 90–92 | 3.7 |
| B+ | 87–89 | 3.3 |
| B | 83–86 | 3.0 |
| B− | 80–82 | 2.7 |
| C+ | 77–79 | 2.3 |
| C | 73–76 | 2.0 |
| C− | 70–72 | 1.7 |
| D+ | 67–69 | 1.3 |
| D | 63–66 | 1.0 |
| D− | 60–62 | 0.7 |
| F | below 60 | 0.0 |
This table is a default, not a fact about your school. Two other scales are in common US use and both are legitimate. A straight-letter scale drops the pluses and minuses and cuts at 90/80/70/60. A seven-point scale uses narrower bands — A from 93, B from 85, C from 77, D from 70 — which moves a large number of grades down one letter compared with the table above: 72% is a C− on our scale and a D on a seven-point one. The same work, a different transcript. Where a page reports a letter it also reports the percentage, and the percentage is the part that transfers between schools. The letter grade to GPA page sets out all three side by side, and the grade charts show what each of them does to a given score.
The 4.0, 4.3 and 5.0 scales
Grade points come from the letter, not from the percentage, and the three scales in circulation differ in exactly one place: what an A+ is worth.
- 4.0 scale. The most common. A+ and A are both worth 4.0 — the plus earns recognition on the transcript but no extra points.
- 4.3 scale. A+ is worth 4.3. Everything below it is identical to the 4.0 scale.
- 5.0 scale. A weighted scale. The base points are the 4.0 figures, capped at 4.0 for an A+; the 5.0 ceiling is reached by the course-level bump described below, not by the letter.
This is worth stating plainly because it is a common source of confusion: on a 5.0 scale an A in a regular class is still 4.0. Nothing about the letter changes. What changes is that an A in an AP class becomes 5.0.
Honors, AP and IB weighting
A weighted GPA adds a fixed bump to the grade points of a harder course before averaging. We use the most widely published bumps: +0.5 for honors, +1.0 for AP, +1.0 for IB, +0.5 for dual enrollment, and nothing for a regular course. Where a page offers a cap, the bumped figure is clamped to it, so a capped 4.0 scale cannot produce a 4.5.
Every GPA page on this site reports the unweighted and weighted figures together rather than making you choose, because the two answer different questions and you are usually asked for both. Bumps vary by district more than any other convention here — some schools weight only AP, some weight honors at +1.0, some cap the weighted GPA at 4.5 — so if your school publishes its own bump table, that table wins.
Pass/fail, withdrawals and zero-credit courses
The grades P, NP, W, I and AU carry no grade points. They are excluded from both halves of the average: they contribute no quality points and no credits, so they cannot drag a GPA down or hold it up. The pages report how many courses were excluded rather than silently dropping them, because a GPA computed over four courses when you entered six is a number you should be told about.
A course entered with zero credits is counted as a course but contributes nothing to a credit-weighted average. Some labs and seminars genuinely carry no credit; treating one as if it had a credit of 1 would quietly change the answer.
A grade we do not recognise is reported as unknown rather than assumed. A typo should not become a silent zero.
Course grades: weighted and points-based
Courses are graded in one of two ways and the arithmetic is genuinely different, so the grade calculator asks which one you have.
Points-based. Everything shares one running total: add up all the points you earned, divide by all the points available. A 5-point homework and a 200-point final are weighted automatically by their size, and there is nothing to enter beyond the two numbers per item.
Weighted by category. The syllabus fixes each category's share — homework 20%, quizzes 30%, final 50% — and the size of an individual assignment is irrelevant. Each category is converted to a percentage first, then combined by its weight.
Two behaviours worth knowing on the weighted path. First, if your weights do not add to 100 we normalise by the weight actually entered rather than assuming the missing share is a zero. Categories weighing 20, 30 and 40 are treated as shares of 90, not as 90% of a course with 10% of zeros. Second, a category you have not been graded in yet is not a zero: the weighted grade calculator averages across the graded weight only and reports the ungraded weight separately, so “92% of the work so far” is never confused with “92% of the course”.
What you need on the final
The final grade calculator solves one equation. If your current grade is c, the final is worth a fraction w of the course, and you want t overall, then the score you need is (t − c(1 − w)) ÷ w. The part of the grade already locked in is c(1 − w), which is also the grade you finish with if you score zero on the final; add 100w to it and you have the highest grade still reachable.
Three cases the page handles rather than printing a number and leaving you to interpret it. If the required score is above 100 the target is gone, and we say which targets are still reachable instead. If the locked-in floor already clears the target, the grade is secured regardless of the final. If the final carries zero weight it cannot move the grade at all. And rather than answering only about the target you typed, the page solves for every letter at once, because the question people actually have is usually “what can I still get”.
Semester grades and exam splits
A semester grade combines two marking periods and an exam on a district-set split — 40/40/20 is the most common, with 45/45/10 and 30/30/40 also widely used. A custom split is normalised to its own total, so a district that writes 45/45/10 and one that writes 0.45/0.45/0.10 get the same answer, and one that writes 4/4/2 does too.
A blank exam is not a zero. If the exam carries weight but has no score yet, the grade is reported across the two marking periods alone and flagged as pending, so the page is clear about which of the two questions it just answered.
Class rank and percentile
Two conventions produce different percentiles from the same rank, and neither is wrong.
The exclusive method — our default — is (1 − (rank − 1) ÷ (size − 1)) × 100. It puts the top student at the 100th percentile and the bottom student at the 0th, which is what most US high schools mean by class rank. The simple method is (size − rank) ÷ size × 100, which never quite reaches 100. Rank 1 of 50 is the 100th percentile under the first and the 98th under the second. The class rank calculator shows both and labels which is which. Decile and quartile are computed from the top-percentage figure, rank ÷ size, and always rounded outward to the containing band.
Curves
The grade curve calculator implements three methods and compares them on the same set of scores, because “curving” means at least three different operations depending on who is saying it.
- Flat shift. Add the same number of points to every score, chosen either directly or by naming a target class average. Preserves the gaps between students exactly.
- Square root. Each score becomes 10 × √score. Helps low scores far more than high ones — 36 becomes 60, while 81 becomes 90.
- Top score to 100. Every score is scaled by 100 ÷ the highest score in the class. Proportional, and entirely dependent on one student.
All three are capped at 100 and floored at 0 by default. The page reports the class mean before and after and how many students cross the pass mark, because that — not the shape of the transformation — is what a curve is usually chosen for.
Test scores and partial credit
A test score is score ÷ total × 100, and the total may be points rather than questions. Half marks are accepted: 34.5 out of 40 is a valid input.
The test grade calculator and every page in the grade charts also show the two adjacent scores — one more right, one fewer — because that is the question that follows the first one. Those neighbour lines appear only on whole-number scores: 34.5 out of 40 has no “one more right”, and inventing one would be arithmetic dressed up as advice. The easy grader is the same calculation with the input reversed, for marking a stack rather than checking a single paper.
The arithmetic exists twice
Every answer on this site is written into the HTML at build time and recomputed in your browser when you change an input. That means the grade maths exists in two implementations: one in the page templates and one in the JavaScript module. Two copies is a real risk of the two quietly disagreeing, so it is checked rather than trusted.
The scale tables live in exactly one file and both implementations read it; a test run diffs the two copies row by row and fails if they differ. A second test renders every calculator page and compares the server-written answer against the answer the browser engine produces for the same inputs, string for string. A divergence stops a release rather than shipping as a number that flickers and changes the moment the page finishes loading.
The practical benefit to you is that the answer is correct before any script runs — on a slow connection, with JavaScript blocked, or in a search result preview.
What a calculator cannot know
Everything above is a model of a general US grading system. The places it stops being reliable are specific and worth naming.
- Your school's percentage bands. If your school cuts an A at 94, or does not use minus grades, the letters on this site will disagree with your transcript while the percentages still agree.
- Repeat and replacement policies. Whether a retaken course replaces the original grade, averages with it, or leaves both on the transcript is a local rule with a large effect on a cumulative GPA. No calculator can see it.
- Rounding at the institution. Some schools round the final course percentage before assigning a letter and some do not. That decision alone moves 89.5% between a B+ and an A−.
- Weighting that is not published. Dropped lowest scores, extra credit ceilings, attendance components and late penalties are usually in the syllabus and never in the numbers you type in.
- Which GPA a college recalculates. Many admissions offices recompute a GPA from the transcript on their own scale, ignoring the school's weighting entirely.
Where a page can detect one of these it says so on the page rather than here. Where it cannot, the rule is simple: your transcript and your instructor are the authority, and this site is a fast way to check the arithmetic. If a figure here disagrees with an official one, the official one is right and we would like to know — the contact page says how.