School Attendance Percentage Calculator
Calculate your school or class attendance percentage, absences, how many more sessions you can miss, and how many you need to attend to reach a target.
Last updated: July 2026
Attendance percentage
Target planning
How is attendance percentage calculated?
Attendance % = Attended sessions ÷ Total sessions × 100. Absences equal total sessions minus attended sessions. For example, attending 170 of 200 sessions gives 170 ÷ 200 × 100 = 85% attendance, with 30 absences and a 15% absence rate.
How many classes can I miss?
The calculator finds the largest whole number of additional missed sessions that can be added before the full-precision attendance rate falls below your target. It assumes you attend no additional sessions before those absences. This is mathematical capacity relative to the entered target, not advice to skip classes.
How many classes do I need to attend?
If the current rate is below the target, the calculator finds how many consecutive future sessions must be attended without another absence. It uses (attended + future attendance) ÷ (total + future attendance) and verifies the first whole-session count that reaches the target.
Classes, lectures, sessions, or school days
The same ratio works for school days, college classes, university lectures, courses, and training sessions. Enter consistent counts: the attended number must describe the same type of session as the total.
Attendance target policies vary
This calculator does not assume that 75%, 80%, 90%, or any other percentage is universally required. Check the policy for your school, university, course, or program, then enter the target that applies to you.
Worked attendance examples
170 attended out of 200
170 ÷ 200 × 100 = 85% attendance. There are 30 absences and the absence rate is 15%.
25 attended out of 30
The full result is 83.333333…%, displayed as 83.33%. Five sessions were missed.
Maximum absences at an 80% target
With 90 attended out of 100, 12 additional absences leave 90 ÷ 112 ≈ 80.36%. A thirteenth gives 90 ÷ 113 ≈ 79.65%, below the target.
Recovering to an 80% target
With 70 attended out of 100, attending the next 50 sessions produces 120 ÷ 150 = 80%. Forty-nine sessions would remain below the target.
Already above a 90% target
With 92 attended out of 100, the target is already met. Two additional absences leave approximately 90.20%; three would reduce the rate to approximately 89.32%.
Perfect attendance and exact recovery
Fifty out of fifty is 100%. However, 49 out of 50 cannot return to exactly 100% through any finite number of later attended sessions because the earlier absence remains in the total.
Starting from zero attended
With 0 attended out of 20, reaching 75% requires 60 consecutive attended sessions: 60 ÷ 80 = 75%.
Frequently asked questions
How do I calculate attendance percentage?
Divide classes or days attended by the total held, then multiply by 100.
How many classes can I miss and keep my target attendance?
Enter your current totals and target. The calculator finds the maximum additional whole absences before the rate falls below that target.
How many classes do I need to attend to raise my attendance?
If you are below target, the result shows how many consecutive future sessions must be attended without another absence to reach it.
Can I get back to exactly 100% after missing a class?
No. Later attendance can approach 100%, but a prior absence prevents the exact ratio from returning to 100% in a finite number of sessions.
Does this calculator know my required attendance percentage?
No. Enter the target required by your school, university, course, or program.
Can I use this for individual classes?
Yes. The formula works for classes, lectures, school days, or any other consistently counted sessions.