Grade Percentage Calculator

Short answer first: multiply each category score by its weight, add those up, and you have your overall grade. Homework 92 at 20%, quizzes 84 at 30%, exams 78 at 50% gives you 82.6%. This grade percentage calculator does that for you, and it also handles the annoying middle-of-term case where some categories are still empty.

How to fill it in

Grab your syllabus. Somewhere near the bottom there's a grading breakdown with percentages, and those should add to 100. Type each category's weight and your average in it. Skip anything that hasn't been graded yet. Don't type a zero for it.

Here's that example as a table:

18.4 + 25.2 + 39 = 82.6%.

Look at what happened there. The 92 in homework looks nice, but exams are half the grade, so the 78 does most of the steering. Students are often surprised by this.

The math behind it

Overall % = Σ (weight × score) ÷ Σ (weights you've entered)

When every category is filled in, the weights add up to 1 and the division doesn't change anything. Midway through a term it matters a lot. Say only homework and quizzes are graded. You have 18.4 + 25.2 = 43.6 points out of a possible 50, so your grade right now is 43.6 ÷ 0.50 = 87.2%. That's a snapshot. The exams haven't had their say yet.

If you want the long version, with a couple more worked cases, there's a post on how weighted grades work on our blog.

Where the numbers go wrong

• Plain averaging. (92 + 84 + 78) ÷ 3 = 84.7. That's about two points higher than the real grade, and it's the most common way people fool themselves.
• Weights that add to 95 or 105. A typo in the syllabus, or participation listed somewhere else. Double-check before you trust the result.
• Raw points in a percentage box. If the quiz category shows 126/150, convert it to 84% first.
• The dropped quiz. Lots of teachers drop your lowest one. Take it out before you average that category.

Some classes don't use weights at all and just pile up points. If your gradebook shows something like 412/460 with no categories, the points-based grade calculator is the right tool, and it can give a noticeably different answer. Once you have a percentage you trust, the letter grade calculator shows where it lands.

Quick gut check: your overall grade has to fall between your lowest and highest category. If it doesn't, a weight got typed wrong.

A real-life case: the lab category

Here's one that comes up in science classes. Labs are 15% of the grade, and you have four lab reports scored 18/20, 17/20, 9/10 and 27/30. Don't average 90, 85, 90 and 90 to get 88.75. If your teacher averages the category by points, it's 71 out of 80, which is 88.75 too in this case. Lucky. But swap the 9/10 for a 6/10 and the two methods split: points give 68/80 = 85%, while averaging the percentages gives 81.25%.

Small difference? On a 15% category that 3.75-point gap shifts your overall grade by about 0.6 points. Not much, unless you're sitting at 89.7.

Ask your teacher which way the gradebook averages. It takes ten seconds.