How to calculate attendance and the classes you can miss

Steps

1. Count the classes you attended and the total classes held so far. Here: 60 and 90.
2. Divide and multiply by 100: 60 ÷ 90 × 100 = 66.67%.
3. To reach a required level R (as a decimal), find x so that (attended + x) ÷ (held + x) ≥ R: x = (R × held − attended) ÷ (1 − R).
4. For 75%: (0.75 × 90 − 60) ÷ 0.25 = 30 classes in a row.
5. Or enter the numbers in the attendance calculator.

When you are above the requirement

If you have attended 80 of 90 classes, your attendance is 88.89% and you can still miss 16 classes and stay at or above 75%. The calculation is m = attended ÷ R − held, which is 80 ÷ 0.75 − 90 = 16.67, rounded down to 16.

If you have attended 45 of 60 classes you are exactly at 75%, so you can miss none of the next ones without falling below.

A higher requirement is much harder to recover

If you attended 30 of 60 classes, you are at 50%. To reach 80% you would need to attend the next 90 in a row, since (0.8 × 60 − 30) ÷ 0.2 = 90. The lower your attendance and the higher the requirement, the more classes it takes, so recover early rather than late.

Check the rules

The required percentage differs between institutions and sometimes between subjects, and a medical certificate or approved leave may count. The calculator assumes that every future class you attend counts and that the total held keeps growing, so confirm the actual rule and the number of classes still to be held with your institution.