About

Most academic arithmetic is simple in principle and easy to get wrong in practice, because the averages involved are weighted ones. A GPA is weighted by credit hours. A course grade is weighted by category or by points. Treat either as a plain average and you get an answer that looks plausible and is wrong by a tenth of a point — which is exactly the margin that decides honors, eligibility and scholarship thresholds.

So every calculator here does two things: works out the answer correctly, and shows the working. A per-course or per-assignment breakdown sits under every result so you can check the total rather than take it on trust.

Everything works without an account. An account adds saved calculations, semesters and GPA goals — persistence, not access. No result on this site is behind a sign-up.

• College students working out a semester or cumulative GPA, what they need to reach a target, or what a retake would do.
• High school students dealing with weighted and unweighted scales, and the Honors and AP bonuses that differ from school to school.
• Anyone mid-term who needs to know what a final exam can still change — in both directions.
• Teachers grading a stack of papers, where a fast, correct percentage matters more than a feature list.

The tools are built for the US grading conventions these audiences use. Where a convention is not universal, the page says so rather than presenting one school's rule as the standard.

Each calculator is a thin page over a shared calculation engine. The engines are plain, self-contained code with no knowledge of the web: they take numbers, return results, and are the only place arithmetic happens. That is what makes them testable, and they are tested heavily — every engine has unit tests whose expected values were worked out by hand and written into the test as a comment, so a test that passes for the wrong reason is visible.

Calculators update as you type, which means the arithmetic exists twice: once on the server and once in the browser. Two implementations of the same formula drift. So every displayed figure, letter grade and message is compared between the two, case for case, by an automated test. That test has caught real divergences — in one case the two implementations disagreed about how to round 3.005, which would have shown one answer on screen and a different one in a saved calculation.

Beyond that, every calculator page is loaded in a real browser and checked for JavaScript errors on every test run. That layer exists because of a failure: a startup-order bug once broke every calculator on the site while more than eight hundred passing tests reported everything as fine. Tests that assert markup cannot see a page that does not run.

Worked examples in the guides are held to the same standard. Each one is computed by hand and then re-run through the engine behind the calculator it describes, because a guide that disagrees with its own calculator is worse than no guide at all.

This is the most important caveat on the site, and it applies to every page. US schools differ on:

• whether plus and minus grades carry distinct point values;
• whether an A+ is worth 4.0 or 4.3;
• what percentage range each letter covers;
• how much an Honors, AP or IB course is weighted, and which courses qualify;
• whether a repeated course replaces the original grade or sits alongside it;
• which courses count toward a GPA at all;
• what attendance is required, and what counts as an excused absence.

Two accurate GPAs for the same student at two institutions can differ noticeably. Nothing here presents a scale as official: defaults are described as common, every one can be changed, and where a result depends on institutional policy the page says so and points you at the syllabus or registrar.

These are planning tools. Your transcript, your gradebook and your registrar are the authoritative record, and they are worth checking before a decision that matters.

A calculator that returns a wrong number is a defect, and it is treated as one. If a result here disagrees with your syllabus, your gradebook or your registrar, we would rather know than not.

Every calculator page carries a reporting form at the foot, which comes pre-attached to the page it was sent from. An email address is optional — you should be able to flag a wrong formula without handing one over. Reports that identify an incorrect result are looked at before anything else.

When a calculation turns out to be wrong, the fix goes in with a test that reproduces the error, so the same mistake cannot return quietly.

For anything that is not about a specific calculator, the contact form reaches the same place.

There are no expert credentials behind these pages, and inventing some would be the easiest way to make a tools site look trustworthy while making it less so. What is offered instead is verifiable: the working is shown on every result, the sources of variation are stated rather than hidden, and where a question cannot be answered by arithmetic the page says so.

That last point matters more than it sounds. A target GPA can become unreachable in the credits you have left; a grade can be out of reach whatever you score on the final; an attendance requirement can run out of classes. When that happens the calculator says so directly and shows the best outcome still available, rather than printing a number above 100% and leaving you to work it out.

What is not offered: admissions advice, study strategy, predictions about what a particular school will accept, or any suggestion that a number here will match your institution's own. Those are not things a calculation can settle.