What you need on the final

Your teacher or syllabus will say how much the final counts, like 10%, 15% or 20% of your grade. That number is the weight. Everything else you did in the class makes up the rest.

So if the final is worth 20%, the grade you have now counts for the other 80%. Your end grade is a mix of the two: 80% of what you have now plus 20% of what you get on the final.

Flip that mix around and you get the score you need. Write the weight as a decimal, so 20% becomes 0.20.

Needed on the final = (target − current × (1 − weight)) ÷ weight

Target is the grade you want to end with. Current is your grade right now, before the final. Always round the answer up, since landing just below it isn’t enough.

1. Multiply your current grade by (1 − weight). This is how much your work so far is worth.
2. Subtract that from your target. This is what the final still has to bring.
3. Divide by the weight. That is the score you need on the final.

Sam has a 78% in chemistry. The final is worth 15%, and Sam wants to finish with an 80%, a B-. Here is the math, one step per line.

Some classes don’t use percent weights. Every assignment is just worth points, and your grade is points earned divided by points possible. You can still find the weight: it is the final’s points divided by all the points in the class, final included.

• Use your grade without the final in it. If the final already shows as a zero in your grade book, your current grade is too low and the answer will be wrong.
• Check that all your work is graded. A missing score or a late assignment that hasn’t been entered yet can change the picture.
• Find out if your school rounds. On a scale where 89.5 rounds up to an A, aim your target at 89.5, not 90.
• If your school builds the final grade from quarter letters, like HCPSS does, the percent formula doesn’t apply. Use the letter rules instead.

Sometimes the formula says you need more than 100%. That means the target can’t be reached through the final alone, unless the final has extra credit. It happens most when the final counts for only a small part of the grade, or when your current grade is far from your target.

• Check the rounding first. If 89.5 counts as an A, the example above drops to 103.5. Still over, but closer.
• Ask your teacher, politely and early, if any missing work can still be turned in or if there is a retake or extra credit. Do this before the term ends, not after.
• Pick a new target that is in reach. Keeping a solid B with a strong final is still worth the effort.
• Think about your other classes. If one final can’t change your letter, your study time may help more somewhere else.

The same formula tells you the lowest score that still keeps a grade. Say Sam from the example above only needs to stay at a C, which starts at 70%. Then (70 − 66.3) ÷ 0.15 = 24.7. Even a weak final keeps the C. Knowing that can take a lot of pressure off.

To see what a zero would do, multiply your current grade by (1 − weight). For Sam that is 66.3%, the floor if the final went as badly as possible.

Once you know the score you need, you know how hard to push. Needing a 60 means steady review is enough. Needing a 92 means you should start early and practice with real problems, not just reread your notes. Look at old tests and quizzes from the class, since finals usually pull from them, and spend most of your time on the topics you missed most.