How Dropping the Lowest Score Changes an Average
Dropping the lowest score increases or preserves an equal-weight average because the smallest value is removed from the set being averaged.
Method
- List the score percentages that have equal weight.
- Choose how many lowest scores the syllabus drops.
- Sort the scores from lowest to highest and remove that number.
- Average the remaining scores.
Worked example
70, 80, 90 and 100 average 85%.
Dropping 70 leaves 80, 90 and 100.
The adjusted average is 90%.
Notes
- Do not use a simple score average when assignments have different point values.
- Weighted categories need a weighted-grade method.
- The official gradebook may apply drop rules only within one category.
- Dropping a score can interact with category weights, missing-work rules and minimum-assessment requirements. The simple equal-weight average is appropriate only when the relevant scores really share the same weight; otherwise recalculate inside the grading structure used by the course.
Dropping a score is simple only when assignments are equally weighted
For equal-weight scores, remove the selected lowest value and recompute the average from the remaining scores. If assignments have different point values or category weights, dropping one score changes both the numerator and denominator differently, so a simple arithmetic average may be wrong.
Some gradebooks drop the lowest item inside a category rather than across the entire course. Apply the rule in the same location as the syllabus; do not compare a homework drop with an exam drop as if they were interchangeable.
Check ties and multiple-drop rules explicitly
When several scores share the same minimum, dropping any one of them produces the same average in an equal-weight model. If two or more scores are dropped, remove exactly the number allowed and recalculate once from the remaining set.
A drop rule changes the grade calculation, not the underlying learning record. Keep the original scores available so the result can be audited if the course policy changes or the gradebook uses a different convention.
Editorial review and limitations
Continue with the related tools
Use the linked tools for your own inputs and scenarios.
- Grade Percentage Calculator — Convert points earned and points possible into a percentage, letter grade and number of missed points.
- Weighted Grade Calculator — Calculate a weighted course grade from category scores and weights, even when the entered weights do not add to exactly 100%.
- Assignment Grade Impact Calculator — Project how an assignment changes your accounted course average or calculate the assignment score needed for a target accounted grade.