A grade calculator is a small piece of arithmetic wrapped in a lot of edge cases. We get asked reasonably often how ours work and why a result sometimes differs from a university portal, so this is the answer in full.
The formula
Every tool on the site uses the weighted average, which is the standard almost everywhere:
Average = (sum of grade point multiplied by credits) divided by (sum of credits)
A course with four credits influences the result twice as much as one with two. This is the single most important property, and it is the thing that simple averaging gets wrong.
The SGPA calculator applies it to one semester. The CGPA calculator applies it across all semesters, weighting each by its credit load — which is why a light semester with excellent grades moves your cumulative figure less than students expect.
Why a result might differ from your university portal
Four causes account for nearly all reports we receive.
1. A different institutional rule
Universities vary on whether a repeated subject replaces, averages with, or sits alongside the original grade. They vary on whether audit courses count. Some exclude the lowest result, some weight the final year more heavily.
No general calculator can know your institution’s rule. Apply it to your inputs first, then calculate. Our backlog impact calculator exists specifically for modelling the repeat cases.
2. Credit values entered from memory
The most common cause. Credits get misremembered far more often than grades, because nobody thinks about them. Take them from the transcript, not from recollection.
3. Mixed scales
Transfer or study-abroad credits often arrive on a different scale and must be converted before averaging, not after. Converting after averaging gives a plausible-looking number that is wrong.
4. Rounding
We carry full precision through the calculation and round only at display. Some institutions round each semester before combining, which can shift the final figure by a few hundredths. Neither approach is incorrect; they are different conventions.
How we check the tools
Each calculator is tested against worked examples taken from published university handbooks across several grading systems, including 10-point and 4-point scales and percentage-based conversions. We test the boundaries too: zero-credit courses, a single subject, all-identical grades, and the maximum and minimum possible results.
Conversion tables — such as those behind the CGPA to percentage converter — follow the published formula of the system selected, because there is no universal conversion between scales. Where a university publishes its own multiplier, that published figure always takes precedence over any general approximation.
What the tools do not do
They do not store your grades. Nothing you type is sent anywhere or kept after you close the page. There is no account and no login, which is also why we cannot recover a calculation for you later — if you want a record, note the number down.
They are also not an official record. For anything that matters — an application, a scholarship, a visa — use the figure on your transcript. Ours is for planning, checking and understanding.
Reporting something that looks wrong
If a result does not match what you expect, tell us through the contact page and include the grades and credits you entered, your grading scale, and the figure you expected. That is enough to reproduce it, and it is genuinely useful — several improvements to the tools have come from exactly these messages.