Dropping the Lowest Score: How It Changes Your Average and Grade
October 29, 2026
Many courses drop the lowest quiz or homework score. To compute the new average, remove the lowest value and average the remaining ones. With quiz scores of 80, 90, 70, 100, and 60, the sum is 400, and the average is 80. Dropping the 60 leaves 340 across 4 quizzes, an average of 85.
The effect of the drop is (average of the rest) − (original average). Here, 85 − 80 = 5 points. The lower the dropped score compared with the others and the fewer the quizzes, the bigger the effect.
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Open the Average Calculator →How Much Does the Drop Help?
With n scores summing to S and a lowest score m, the new average is (S − m) ÷ (n − 1). Dropping a 60 from five quizzes helps 5 points; dropping a 60 from ten quizzes (sum 800, average 80) gives (800 − 60) ÷ 9 = 82.2, a gain of only 2.2 points. If the lowest was a zero from a missed quiz out of five with the others averaging 85: before the drop the average is 68; after it, 85, a gain of 17 points. So a drop policy is most valuable when you have one disastrous score and few assignments.
| Scores | Average before | Dropped | Average after | Gain |
|---|---|---|---|---|
| 80, 90, 70, 100, 60 | 80.0 | 60 | 85.0 | +5.0 |
| Ten scores, sum 800, lowest 60 | 80.0 | 60 | 82.2 | +2.2 |
| 0, 85, 85, 85, 85 | 68.0 | 0 | 85.0 | +17.0 |
| 70, 75, 80, 85 | 77.5 | 70 | 80.0 | +2.5 |
Projecting With the Drop
Suppose you have four quiz scores 82, 88, 90, and 76 and one quiz left; the lowest of five will be dropped. What do you need on the last quiz to average 90? If you score x ≥ 76, the 76 is dropped: the average of 82, 88, 90, and x must be 90, so x = 360 − 260 = 100. If x < 76, then x is dropped, and the remaining average is (82 + 88 + 90 + 76) ÷ 4 = 84. So you need a perfect score to reach 90. If the target is 87: x = 348 − 260 = 88. The drop policy therefore lets you put the 76 behind you only if the last score beats it.
Policy Details to Check
Does the drop apply to one assignment category (quizzes) or across several? Is it the lowest percentage or the lowest raw points? Are makeup assignments counted? Some instructors drop the lowest score only after the last quiz. If categories are weighted, compute the category average with the drop, then apply its weight. Don't skip optional assignments assuming they'll be dropped: if all scores are similar, the drop gives little and one missing assignment counts as a zero.
Strategy
Use the drop to cover an unavoidable bad day, and don't plan to skip. Track your grade in a spreadsheet using SMALL or MIN functions to find the lowest score: =(SUM(range) − MIN(range)) ÷ (COUNT(range) − 1).
Frequently Asked Questions
How do I compute the average after dropping the lowest score?
(Sum − lowest) ÷ (count − 1).
When is the drop most valuable?
When there is one very low score and few assignments.
What if I skip an assignment?
It counts as a zero, which may be the dropped score.
Does the drop apply to every category?
Check the syllabus.
How do I do it in a spreadsheet?
=(SUM(range)−MIN(range))/(COUNT(range)−1).