How attendance percentage is calculated
Divide the days you attended by the days held so far and multiply by 100.
Attendance % = attended ÷ total × 100
Example: your attendance rate
83 days attended out of 90.
- Attendance: 83 ÷ 90 × 100 = 92.22%
- Missed: 90 − 83 = 7 days
Days in a row needed to reach a target
Attending n more days in a row adds n to both the days attended and the total. You need the new rate to reach the target, which gives the smallest whole n from this formula.
n = (T × total − 100 × attended) ÷ (100 − T), rounded up
T = target attendance (%). If the rate is already at or above T, n is 0. Reaching 100% is only possible if no day has been missed.
Example: reaching 95%
83 of 90 attended, target 95%.
- Days needed: (95 × 90 − 100 × 83) ÷ (100 − 95) = 250 ÷ 5 = 50 days
- Check: (83 + 50) ÷ (90 + 50) × 100 = 133 ÷ 140 × 100 = 95%
Days you can miss
If R days are still to come and you miss m of them, you finish with {attended + R − m} days attended out of{total + R}. Keeping that at or above the target gives the most you can miss.
m = attended + R − T × (total + R) ÷ 100, rounded down
R = days still to come, T = target attendance (%). If even attending every remaining day falls short of T, the answer is “Not possible”.
Example: keeping 90%
83 of 90 attended, 90 days still to come, target 90%.
- Most you can miss: 83 + 90 − 90 × (90 + 90) ÷ 100 = 173 − 162 = 11 days
- Check: (83 + 90 − 11) ÷ (90 + 90) × 100 = 162 ÷ 180 × 100 = 90%. One more miss gives 89.44%, below the target.
Questions
What attendance percentage counts as chronic absence?
In the U.S. Department of Education’s measure, as described in a National Academy of Medicine discussion paper, a student is chronically absent after missing 10% or more of enrolled school days [1]. That is the same as attending 90% or less. Employers and schools set their own attendance rules, so check yours.
Do excused absences count?
For chronic absenteeism, yes: the measure counts all absences, excused or not [1]. For a specific school’s or employer’s policy, check that policy. Count only the days that your policy counts.
Why can I never get back to 100%?
Once a day is missed, the total goes up with every day you attend but the missed day stays on the record, so the rate approaches 100% without reaching it. The calculator says “Not possible” instead of giving a made-up number.
What is the difference between “days to reach a target” and “days I can miss”?
“Days to reach” looks ahead from a rate that is too low and asks how many days in a row you must attend. “Days I can miss” starts from a rate you want to keep and asks how many of the days still to come you can skip. For that you need to say how many days are still to come.
Can I use it for work?
Yes. Switch to workplace wording and enter days (or shifts) worked and scheduled. It is a plain rate and does not know any employer’s rules.