Attendance Calculator
Track your attendance percentage and how many classes you can still miss.
Please note: Provided for learning and for checking your own working. Institutions differ in the conventions and rounding they apply, so confirm the method against your own course materials.
What the Attendance Calculator does
Attendance percentage is classes attended divided by classes held. Because each absence both fails to add to the numerator and adds to the denominator, the percentage falls faster than most people expect — and recovering from a shortfall takes disproportionately many consecutive attendances.
Formula
Attendance = Attended ÷ Held × 100Classes you can miss = ⌊Attended ÷ Target − Held⌋Classes you must attend = ⌈(Target × Held − Attended) ÷ (1 − Target)⌉
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Classes attended | number | Yes | Accepts 0 or more. |
| Classes held so far | number | Yes | Accepts 0 or more. |
| Required attendance | % | Yes | — |
| Total classes in the term | number | Optional | Optional — lets the calculator work out your best and worst possible finish. Accepts 0 or more. |
How to use it
- Enter Classes attended, Classes held so far and Required attendance.
- Optionally add Total classes in the term.
- Select Calculate.
Worked example
Attended 42 of 50 classes with a 75% requirement.
- Attended
- 42
- Held
- 50
- Required
- 75%
42 ÷ 50 = 84%, comfortably above the requirement. You can miss 6 more classes (42 ÷ 0.75 − 50 = 6) before dropping below 75%.
Reading the result
- "Classes you can still miss" is explicitly a consecutive-from-now figure, per the notes — it is not a total allowance for the rest of the term, since attending in between resets the math each time.
- The "attendance if you miss more" table shows the compounding effect concretely — the percentage does not fall linearly, so it is the tool to use to find exactly where the cliff edge is rather than estimating it.
Assumptions and limitations
- "Best possible" and "worst possible" final attendance (when a term total is entered) bracket the range assuming perfect or zero attendance from here — neither extreme is typical, so the true likely outcome is not itself computed.
- The whole calculation treats attendance as one course-wide ratio — the notes flag that many institutions calculate it per subject, so a comfortable overall figure can still hide one specific class already failing its own threshold.
Common mistakes
- Banking "classes you can still miss" as a fixed total rather than a from-today figure — it needs recalculating after every change in attendance, not treated as a one-time budget.
Frequently asked questions
Why does recovering attendance take so many classes?
Because every class you attend adds one to both the numerator and denominator, which moves the ratio only slightly. At 60% with a 75% target, you need to attend three classes for every one you previously missed.
Does the calculator account for classes not yet held?
Yes, if you enter the term total. It then shows your best and worst possible finish and exactly how many of the remaining classes you must attend.