How to Calculate a Weighted Grade

Your grade isn't the average of your scores

Homework 92, quizzes 85, tests 84, final 88. Average those four and you get 87.25.

Your actual grade is 86.75% — because the categories aren't equal, and your worst score is sitting in the heaviest one.

The arithmetic

Multiply each score by its weight, add them up, divide by the total weight.

Category	Weight	Score	Weight × score
Homework	20%	92	1,840
Quizzes	15%	85	1,275
Tests	40%	84	3,360
Final	25%	88	2,200
	100%		8,675

8,675 ÷ 100 = 86.75%

Work on the heaviest category, not the weakest

This is the practical point, and it's the opposite of most people's instinct.

The instinct is to fix whatever score looks worst. The arithmetic says something else:

• Ten points in a category worth 40% → 4 points on your grade
• Ten points in a category worth 10% → 1 point on your grade

Same effort, four times the result. If your weakest score sits in your lightest category, it's costing you far less than it feels like it is — and the hours spent rescuing it would move your grade more if they went somewhere heavier.

That's why the calculator shows what ten points on the final are worth. At 25% weight, ten more points move your overall grade by 2.5. At 5% weight, the same ten points move you by half a point. Knowing which before you decide how to spend a weekend is the whole value.

The weights have to add to 100

The calculator shows your weight total as its own figure, because it's the thing most likely to be wrong.

If it isn't 100, you've either mistyped something or forgotten a category. The grade is divided by the total you actually entered rather than by 100 — so a three-category course still works, and a partial entry gives a sensible answer instead of a silently deflated one.

But if you expected 100 and got 85, go back to the syllabus.

What this can't model

A weighted average assumes every item inside a category counts equally. Plenty of courses add rules on top:

• Dropping the lowest quiz
• Replacing your lowest test with the final if the final is higher
• Extra credit that lands inside one category

None of those are weighting — they're decisions about what goes into a category average. Work them out first, then enter the result. The calculator takes your category averages as given.

Read the syllabus once, properly

Three things are settled there, and guessing at any of them makes every number on this page slightly wrong:

1. Ten-point or seven-point scale? On a seven-point scale an A starts at 93, not 90.
2. Plus and minus grades? They change what an 89 is worth considerably.
3. How does it round? Does 89.5 become an A?

Five minutes at the start of term, and you stop guessing for the rest of it.

Do this in week six, not week fifteen

The value of working out your grade is knowing what you need while there's still time to do something about it.

Filled in during the final week, this is a prediction. Filled in halfway through, it's a plan — you can see which category carries the most weight, where you actually stand, and how many points you're chasing.

Print the course grade planner, copy the weights off your syllabus once, and update it as scores come back.

Grade scales vary by school and country — your syllabus is the authority.