Why one class changes both sides of the ratio
Attendance moves according to both classes attended and classes held, so the denominator matters as much as the numerator. A missed class and an attended class change those two counts differently.
After an attended class, add one to both attended and held. After a missed class, add one only to held. This is why attendance rises more slowly near a high total and why subtracting a fixed percentage point is incorrect.
- Attend next class: (attended + 1) ÷ (held + 1) × 100.
- Miss next class: attended ÷ (held + 1) × 100.
Worked example from a 72 percent starting point
Suppose the record is 72 attended classes out of 100. Attending the next class produces 73 ÷ 101 × 100 = 72.28%. Missing it produces 72 ÷ 101 × 100 = 71.29%.
For a 75% target, attending 12 consecutive classes produces 84 attended out of 112 held, exactly 75%. The required count comes from solving the ratio with future attended classes added to both totals.
Build a useful next-class comparison
Write down the present attended and held totals, model the next class as either attended or missed, and compare both outcomes. Extending the same table across several classes makes the direction and pace of change visible.
- Start from unrounded attended and held counts, not only the portal percentage.
- Keep attended and missed scenarios in separate rows.
- Recalculate when the timetable or recorded count changes.
Checks before acting on the result
Do not add or subtract a fixed percentage point for every class; the change becomes smaller as the total class count grows. Confirm what the institution includes as a held class before relying on the projection.
- Confirm whether lectures, labs, and tutorials are counted together or separately.
- Treat leave, condonation, and rounding as institution-controlled rules.
- Use the attendance calculator for a longer recovery or absence scenario.
Frequently asked questions
Why does attending one class not add one percentage point?
Because the attended count and the held count both increase. The change depends on the starting totals, so it becomes smaller as more classes accumulate.
What happens to the formula when a class is missed?
Only the held count increases: new attendance is current attended divided by current held plus one. A missed class never increases the attended numerator.
Should subjects be combined in one attendance calculation?
Only if the applicable institution rule combines them. If attendance is enforced by subject or component, calculate each subject separately so an overall rate cannot hide a shortage.