How the needed score is worked out
Your overall grade after the final is a blend of two numbers: the grade you have now, which counts for everything except the final, and your final exam score, which counts for the final's weight. Solve that blend for the final score and you get the formula below.
Overall = current × (1 − w) + final × w
Needed on final = (target − current × (1 − w)) ÷ w
w = final exam weight ÷ 100
The calculator runs this for the grade you typed and for the lowest percent of every letter, so you can see at a glance which letters are in reach. Any needed score above 100% is marked out of reach, and any at or below 0% is marked locked in.
Worked example
You have an 88.5% going into a final worth 20% and you want a 90% overall.
- What you have already counts for 80%: 88.5 × 0.8 = 70.8 points.
- The final has to supply the rest: 90 − 70.8 = 19.2 points.
- Those points come from 20% of the final: 19.2 ÷ 0.2 = 96% needed.
For an A at 93% you would need (93 − 70.8) ÷ 0.2 = 111%, which is out of reach. For a B at 83% you would need just 61%. The other way round: score 80% on the final and you end up with 70.8 + 0.2 × 80 = 86.8%, a B. These numbers are loaded when the page opens.
When the answer is over 100% or below 0%
- Over 100%. The target cannot be reached with the final alone. The ticket shows the highest grade you can still get, which is your grade with a perfect final.
- 0% or below. The grade is already safe. The ticket shows the lowest grade you can end up with, which is your grade with a zero on the final.
Limits
- Your school's policy wins. Some classes require a minimum score on the final to pass, replace a low test with the final, or curve the exam. None of that is in this formula.
- If the final is graded in points, convert your expected score to a percent first.
- The default letter cutoffs are a common US plus and minus scale (A at 93, A- at 90 and so on, F below 60). Change them under "Letter grade cutoffs" to match your syllabus.
- Need your current grade first? Work it out from your assignments with the grade calculator.
Questions people ask
How do I calculate what I need on my final?
Take the grade you want, subtract what your current grade already contributes, and divide by the final's weight. As a formula: needed = (target − current × (1 − w)) ÷ w, where w is the final's weight as a decimal. With an 88.5% going into a final worth 20% and a target of 90%, that is (90 − 88.5 × 0.8) ÷ 0.2 = (90 − 70.8) ÷ 0.2 = 96%.
What does it mean when I need more than 100%?
It means the grade you want is out of reach on the final alone, unless your teacher gives extra credit or the exam has bonus points. With an 85% and a final worth 20%, even a perfect 100 on the final only brings you to 0.8 × 85 + 0.2 × 100 = 88%. The calculator tells you the best grade you can still reach.
What if the needed score is zero or negative?
Then that grade is already guaranteed: even a 0 on the final keeps you at or above it. With a 95% and a final worth 10%, a zero still leaves you at 0.9 × 95 = 85.5%, so a B is locked in. You should still sit the exam, since many schools have rules about missed finals.
What is my final exam weight?
It is the share of your overall grade the final is worth, and it is usually printed in the syllabus. Typical values are 10% to 25%. If your class is graded on total points instead, divide the final's points by the total points for the whole term, including the final, to get its weight.
Does the calculator round my grade?
The needed scores use the exact cutoffs, so a target of 90% means 90.0%, not 89.95%. That is the safe reading: if your teacher rounds 89.5 up to 90, you may need slightly less than shown. The reverse calculation shows the overall grade to one decimal, rounding a 5 up, and takes the letter from that shown number.
Is my current grade the right number to use?
Use the grade you have before the final, as a percent. If your teacher's online gradebook already counts the final as a zero, it will show a lower number than your real standing, so use the grade from before the final was added or work it out with the grade calculator.