The short answer
Three sentences cover most of it. First, GPA = Σ(grade points × credits) ÷ Σ(credits) — convert each course to grade points using the scale the target school or programme uses, then take a credit-weighted average. The word "weighted" is the load-bearing part, not decoration. Second, always attach the basis to the number: saying "my GPA is 3.6" without saying which scale, weighted or unweighted, and which courses are included, is not a statement. Third, calculate it yourself before you send anything — run your transcript through the GPA calculator using the receiving school's own table and see whether it matches the number on your transcript. If it does not, attach your own breakdown; that saves a round of emails. The three mistakes that cause the most trouble in practice are: reporting a Chinese 4.0 grade point average as if it were a US 4.0 GPA, multiplying an average of 85 by 0.04 and calling the result 3.4 (the relationship is not linear, because letter grades are banded), and forgetting that a retaken course may only count once — most schools take the better attempt, but the programme you are applying to decides.
Reading a conversion table: work out which scale you are on
The first step of any GPA calculation is turning grades into grade points, and that is what a conversion table does. There are two forms. The banded table gives a fixed point value per letter grade: 93 or above is A and 4.0, 85–89 is 3.7, 82–84 is 3.3, and so on. The defining feature is that it is banded rather than continuous — an 89 and a 90 can sit 0.3 apart while an 89.9 and a 90 are identical, because the score only changes when it crosses a boundary. That is why "half a point of average" moving a GPA by a tenth is so common. The linear formula is the other form: multiply the percentage by a coefficient, for instance (score − 50) ÷ 10, which turns 85 into 3.5 on a 4.0 scale. It is used by some Chinese institutions and parts of the British system; its virtue is continuity, its flaw is that it does not map one-to-one onto letter grades. The important consequence: the two methods give different answers, and the same transcript can easily differ by 0.2 to 0.4 in GPA depending on which is used. So step one is always to confirm which table the other side uses — the small print under a GPA requirement usually says "calculated on a 4.0 scale" or "weighted by credit hours", and that line matters more than your own arithmetic.
Weighted average: why it is the right one
Suppose you take two courses: a 4-credit maths module with an A (4.0 points) and a 2-credit sports course with a B (3.0 points). The unweighted average is (4.0 + 3.0) ÷ 2 = 3.50. The credit-weighted average is (4.0 × 4 + 3.0 × 2) ÷ (4 + 2) = 22 ÷ 6 = 3.67. The two differ by 0.17 over a single 2-credit course. Make sports a 1-credit course and the gap widens to 0.25; add a 5-credit module and it widens further. Which one does the school want? Most US programmes, and almost every Chinese GPA, weight by credits, because that answers the question "how many grade points did you earn per credit hour of study" — failing a 5-credit major module should count for more than failing a 1-credit elective. The exceptions are real: some British and Australian programmes use the unweighted average, because their systems work from percentages or classes directly; and graduate applications often want a major-GPA figure that excludes general education and physical education entirely. The accurate summary is that both are legitimate bases, and the difference is which one they want. When in doubt, calculate both, and when you report, state the basis — that is always safer than sending a bare number.
Chinese grade points and US GPA: why you cannot convert them directly
This is where people most often go wrong. The Chinese "average grade point" on a 4.0 scale uses percentage bands: 90 and above is 4.0, 85–89 is 3.5, 80–84 is 3.0, 75–79 is 2.5, 60–69 is 2.0. A US 4.0 GPA uses different bands: 93 and above is 4.0, 90 is 3.7, 87 is 3.3, 83 is 3.0, 80 is 2.7. The boundaries do not line up, so the same "3.5 on a 4.0 scale" means something quite different in each system — in the Chinese scale, 3.5 means 85 and above; in the US scale, 3.5 corresponds roughly to the 88–90 band. Three further differences get overlooked. First, many Chinese institutions calculate an unweighted average, and a US school will normally recompute with credits. Second, the Chinese 5.0 scale (excellent 5.0, good 4.0, average 3.0) has different band boundaries from a US 5.0 scale, so the two cannot be matched one-to-one. Third, physical education and public politics courses are usually included in the Chinese average but excluded by US institutions when they compute GPA themselves. The practical approach: enter every course from your transcript into the GPA calculator and run it under the Chinese, US 4.0 and percentage bases — three numbers and the relationship between them — then check against the receiving school's published table. You can even feed your percentage average in to see where it lands on the US scale and stop guessing.
Retakes, minors and major GPA: three rules that get missed
Beyond conversion and weighting, three rules actually change your result. How retakes count: the overwhelming majority of schools take the better attempt — if a course was retaken, only the higher grade goes into the GPA and the earlier attempt is excluded (note this is different from "count both and average", which drags the GPA down considerably). A minority of programmes do require both attempts to count, so this is worth confirming rather than assuming. Minors and double degrees: normally only the major's courses feed the main GPA, and a minor can appear on the transcript separately — whether it counts is up to the receiving school, so if you are relying on a minor to lift your average, check first. Major or professional GPA: many graduate programmes ask for a GPA computed from major courses alone, with general education, PE and electives excluded. Your overall GPA might be 3.5 while your major GPA is 3.8, or the reverse when the major is harder. All three versions can appear in one application, so the safest move is to compute all three in advance rather than wait to be asked.
Before you send: a short checklist
What actually decides the outcome is usually process and basis, not arithmetic. Working through the list below prevents most of the back-and-forth. 1. Work from the official transcript: hand-copied transcripts miss a credit, drop a course, or count a retake twice — the course codes, credits and grades on the official document are the only trustworthy source. 2. Find the other side's table: the admissions page, the application FAQ, or the programme's "Academic Requirements" section usually states the scale, whether it is weighted, and what is excluded. Screenshot it — it is the basis for everything you calculate. 3. Calculate it yourself and keep the breakdown: enter each course in the GPA calculator and retain the per-course points × credits, so you can compare with the official figure and either confirm it or send the detail alongside. 4. State the basis when you report: something like "GPA 3.65 / 4.0 scale, credit-weighted, 45 credits at [school]" lets a reader check it in one glance. 5. Look at your percentage average too: many admissions staff and agencies still look at it, so send both numbers. The percentage and statistics tools will confirm your average and standard deviation quickly.
想马上动手：用 GPA 计算器 按 4.0 / 5.0 / 百分制 / 中国绩点制分别算一遍，用 百分比计算器 核对百分制均分，用 数学计算器 手验加权公式，看不懂公式先读 进制与换算速查表。Try it now: run your transcript through the GPA calculator on all four scales, check your average with the percentage calculator, verify the weighted formula by hand with the maths calculator, and read the conversion reference table if a formula looks unfamiliar.
FAQ
An average of 85 — what is that on a US 4.0 GPA?
Roughly in the 3.3–3.5 region, but the number is close to meaningless on its own, because a US GPA is computed from bands rather than proportionally. On the common 4.0 table, 85 falls in the 3.3 band (A- is 3.7, which corresponds to 90), and a different school's table might put 85 at 3.5 or 3.7. The accurate method is to convert each course with the receiving school's own table and then weight by credits, rather than back-solving from a single average. There is a widespread misconception here: multiplying by 0.04 (85 × 0.04 = 3.4) is a linear formula used by some Chinese institutions, and it is not the same thing as a US GPA, because the US table is banded — 88 and 89 can have identical points, while 89 and 90 can differ by 0.3. If you have the table, enter the courses directly in the tool; if you do not, treat 3.3–3.5 as a mental ballpark and always attach the basis when you report it.
Can I report my Chinese 4.0 grade point average to a US school?
Not as-is — but do not worry, because most US institutions recompute an official transcript under their own standard algorithm, and the figure you report is only a reference. Three things do matter. Label the basis clearly: "average grade point 3.65/4.0, weighted, general education included" tells a reader exactly what you are quoting. Attach the breakdown: a table of every course with its credits and grade points, sent with the transcript or in the email body, saves a round trip and shows preparation. Pre-compute the US version: run your own transcript through the GPA calculator on the US 4.0 scale. If it lands close to your school's figure, your transcript data is sound; if it differs a lot, the likely reason is that your school included PE or public politics courses that the US algorithm excludes — which is itself a reason to report both numbers and explain the difference.
Does a retaken course count once or twice in my GPA?
The vast majority of schools and programmes take the better attempt only: if a course was retaken, only the higher grade is counted, and the earlier attempt is excluded entirely (which is a different thing from counting both and averaging — that pulls the GPA down noticeably). Some programmes do require both attempts, particularly the more rigorous medical, veterinary and law programmes, so treat this as something to confirm rather than assume. Two ways to confirm: look for an explicit statement in the application FAQ or the programme's academic requirements page, or ask the admissions office directly — and when you ask, make the question specific, for example "I retook one course; does your programme count the best attempt only, or both attempts, and does the same rule apply to the major GPA?" One related caution: a retaken course usually improves your GPA, but if the retake is still a fail, the credits are often deducted, which affects both your total credits and your overall GPA — a heavier consequence than the arithmetic.