Weighted Grade Calculator

Written byOleh Soloninupdated 5 October 2026

Grades

Weights

As many numbers as there are grades.

Result

Weighted average4.571
Plain average4.25
Difference0.321
Total weight7
Grades4
How it was worked out
the products add up to 32, the weights to 7, so 4.571; a plain average would give 4.25

When the exam counts for more than the homework

An average that respects how much each assessment counts, shown next to the unweighted average so the effect is visible.

When the exam counts three times as much as the homework, a plain average lies. The marks "5 4 3 5" with weights "3 1 1 2" give a weighted average of 4.571 against a plain 4.25 — three tenths of a point that exist only because the top mark landed on the heavy piece.

The same marks weighted "1 1 5 1" come to 3.625, six tenths below the plain average: now it is the low mark carrying the weight. Nothing about the marks changed, only what they were given for.

The calculator prints both averages and the difference between them, which is the price of the weighting.

How to use

Enter the marks in the first field, separated by spaces, commas or line breaks.
Enter the weights in the second field, in the same order and the same quantity.
Weights can be any numbers of zero or more, with at least one above zero: 3 and 1 behave exactly like 30% and 10%.
Compare the weighted average with the plain one to see where the heavy pieces pull.

Same marks, different weights

Every row is a calculator run on the same marks, "5 4 3 5". The plain average is 4.25 throughout; the weighted one swings by a whole point.

Calculator runs on the marks "5 4 3 5".
Weights	Weights add to	Weighted average	Plain average	Difference
3 1 1 2	7	4.571	4.25	+0.321
1 1 1 1	4	4.25	4.25	0
5 1 1 1	8	4.625	4.25	+0.375
1 1 5 1	8	3.625	4.25	−0.625

What units the weights should be in

Any units — only the ratios matter. Weights of "3 1 1 2" and "30 10 10 20" give identical results, because the calculator divides the sum of the products by the sum of the weights rather than by a hundred.

It follows that percentages are allowed but not required, and they do not have to add up to 100. If the handbook lists 40, 30 and 20 percent with the last 10 going to attendance, enter the three as they are: the calculation runs against a total of 90.

Equal weights return the plain average, which is the second row of the table. Matching weighted and plain figures do not prove the weights were ignored: grades of 5, 4 and 3 weighted 1, 2 and 1 also average exactly 4. If the match is unexpected, check that the right numbers went in.

What this calculator shows

The weighted average and the plain average for comparison
The difference between them, which reveals where your strong work landed
The total weight and the number of grades counted

What to keep in mind

There must be as many weights as grades; a mismatch is reported rather than guessed at.
Weights can be any numbers of zero or more, as long as at least one is above zero — only their proportions matter, so percentages work as well as multipliers.

FAQs

How is a weighted average calculated?

Each mark is multiplied by its weight, the products are added, and the total is divided by the sum of the weights. For "5 4 3 5" with weights "3 1 1 2" that is 32 ÷ 7 = 4.571.

Do the weights have to add up to 100?

No. The calculator divides by whatever the weights come to, so "3 1 1 2" and "30 10 10 20" give the same answer.

Why is my weighted average lower than the plain one?

Because a low mark fell on a heavy piece of work. In the "1 1 5 1" example the weight backed the three rather than the fives, and the average dropped from 4.25 to 3.625.

What happens if all the weights are equal?

The weighted average equals the plain one. It is a useful check: if the two figures differ, the weights are genuinely doing work.

Where do I find the weights for my course?

In the course handbook or the assessment regulations, which set out what share of the final mark each piece of work carries.

Can a weight be zero?

Yes, and that mark then drops out of the calculation. If every weight is zero there is nothing to divide by, and the calculator says so instead of returning a number.

What if I have more marks than weights?

Check the lists: there has to be exactly one weight per mark. When they do not match the calculator stops and reports how many of each it found.

Worked example

Four pieces with different weights

Input: marks 5 4 3 5, weights 3 1 1 2

Output: weighted 4.571, plain 4.25, difference +0.321

Note: The same marks weighted "1 1 5 1" give 3.625 — six tenths below the plain average.

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