Marks Percentage Calculator - Total, Average, Grade Band and Marks Needed
Enter the marks you got and the maximum for each subject or paper.
Maintained by Hirantha Sandaruwan Lakshan. Updated 13 October 2026.
About this tool
You get the total, the overall percentage, the average mark per subject, a percentage for each subject and a grade band from a small table you can edit. Switch on weights if some papers count for more, and use the last-paper helper to see what you need to reach a target. Nothing you type leaves your device.
How it works
The overall percentage is the total marks obtained divided by the total maximum marks, times 100. Papers with different maximums are weighted by their size: a paper out of 200 counts twice as much as one out of 100. The average mark per subject is the total divided by the number of subjects. The average of the subject percentages gives every subject the same say whatever its maximum. The two averages are equal only when every paper has the same maximum.
With weights on, the weighted percentage is the sum of (weight x subject percentage) divided by the sum of the weights. A subject with 80% and weight 3 plus a subject with 50% and weight 1 give (3 x 80 + 1 x 50) divided by 4, which is 72.5%. A blank weight counts as 1.
Grade bands are tested on the exact percentage, not the rounded one, so 74.99% stays below a cut-off of 75. The default table is an example: A from 75, B from 65, C from 50, S from 35 and W below 35. That is the pattern Nuffic publishes for the Sri Lankan G.C.E. O/L and A/L, and Wikipedia for the O/L, but we could not find the Department of Examinations circular itself, so it is labelled an example and not the official table. Change it to match your school, university or tuition class.
The last-paper helper solves for one unknown. Without weights it finds the smallest mark x in a new paper out of M so that (marks so far + x) divided by (maximum so far + M) reaches your target, and rounds up to the next hundredth of a mark. With weights it does the same sum using the new paper's weight.
Worked examples
Five subjects, each out of 100
Mathematics 78, Science 66, English 71, History 59 and Sinhala 83. The total is 357 out of 500, which is 71.4%, and the average mark per subject is 71.4. With the example bands that is a B (65 to 74).
Papers with different maximums
45 out of 50 and 60 out of 100. Overall it is (45 + 60) divided by (50 + 100), which is 105 / 150 = 70.00%. The average of the two percentages (90% and 60%) is 75.00%, higher because the small paper counts as much as the big one.
What do I need in the last paper?
After the five subjects above, one more paper out of 100 takes the maximum to 600. For 75% overall you need 75% of 600 = 450, minus 357, which is 93 marks. For 60% you need only 3 marks. For 100% it is impossible: full marks give 457 out of 600, which is 76.17%.
Example grade bands (editable, not an official table)
| Grade | Marks | Meaning in the example |
|---|---|---|
| A | 75 to 100 | Distinction |
| B | 65 to 74 | Very good pass |
| C | 50 to 64 | Credit pass |
| S | 35 to 49 | Ordinary pass |
| W | 0 to 34 | Weak (fail) |
Frequently asked questions
How do I calculate a percentage from my marks?
Divide the marks you got by the maximum and multiply by 100. For several subjects, add all the marks you got, add all the maximums, then divide: 357 divided by 500 times 100 is 71.4%.
What is the difference between the overall percentage and the average of percentages?
The overall percentage adds all marks first, so bigger papers count for more. The average of percentages treats each subject equally. They match only when every paper has the same maximum. Your school or university's rule decides which one it uses.
What are the G.C.E. O/L and A/L grade bands?
The pattern published by Nuffic (for the O/L and A/L) and Wikipedia (for the O/L) is A 75 to 100, B 65 to 74, C 50 to 64, S 35 to 49 and W below 35. We could not find the Department of Examinations circular with that table, so treat it as an example and check the Department's notice for your exam year. This tool does not calculate Z-scores.
How do weights work?
Each subject's percentage is multiplied by its weight, the results are added, and the total is divided by the sum of the weights. A weight of 2 counts a subject twice as much as a weight of 1. Leave a weight blank and it counts as 1.
How many marks do I need in the last paper to reach a target?
Enter the target percentage and what the last paper is out of. The helper uses the subjects in the list as the papers already sat. If the answer is more than the paper is worth, it says the target cannot be reached and shows the highest percentage you can still reach with full marks.
Why is my grade different from the one my school gave?
Schools, universities and tuition classes set their own bands and some round up. Edit the grade table to match theirs. This tool tests the exact percentage, so 74.9% is not rounded up to 75%.
Can I enter decimal marks?
Yes, up to two decimals, for example 12.5 or 7.25. Totals are added in hundredths, so 0.1 plus 0.2 is exactly 0.3. Marks above the maximum are refused with a message.
Is my data stored or sent anywhere?
No. Everything is calculated in your browser and nothing is sent or saved.
Sources & references
Updated Oct 13, 2026