Attendance Calculator

Enter the classes you have attended, the classes held so far and the attendance you need, such as 75%, to see your current percentage and either how many classes in a row you must attend to reach it or how many you can miss and stay at or above it.

Free, no signupNo daily limitRuns in your browser - nothing you enter is uploadedUpdated 7 October 2026

Classes attended

Classes held so far

Attendance you need (%)

-Attendance now

-Attendance after that

What if…

Next classes	If you attend all	If you miss all

Worked example: two students, a 75% rule

Below the line. Ayesha has attended 30 of 50 classes (60%).

need x with (30 + x) ÷ (50 + x) ≥ 0.75 x ≥ (0.75 × 50 − 30) ÷ (1 − 0.75) = 7.5 ÷ 0.25 = 30 → attend the next 30 classes: 60 of 80 = 75%

Above the line. Bilal has attended 45 of 50 (90%).

miss y with 45 ÷ (50 + y) ≥ 0.75 y ≤ 45 ÷ 0.75 − 50 = 60 − 50 = 10 → can miss 10 classes: 45 of 60 = 75%

Why the answer is checked, not just calculated

The formulas give a number like 29.6 classes, and you cannot attend 0.6 of a class. Rounding the wrong way is how students end up at 74.9% after "doing the maths". This calculator rounds up the classes you need and down the classes you can miss, then checks the result against the exact percentage, so the answer is always the smallest number that gets you there - or the largest number you can miss without dropping below.

It also catches the cases a formula alone misses: a 100% requirement after a single absence can never be met, and a target you are already above needs no extra classes.

What this calculator does not do

It assumes every future class counts the same and that you attend (or miss) them all in a row.
It does not know any institution's rules on rounding, medical leave or separate lecture and lab attendance.
Results are whole classes checked against the exact percentage, so 74.99% is never rounded up to 75%.

Frequently asked questions

How do I calculate my attendance percentage?

Divide the classes you attended by the classes held and multiply by 100. 30 out of 50 is 30 ÷ 50 × 100 = 60%.

How many classes do I need to attend to reach 75%?

If you attend x more classes in a row, your attendance becomes (attended + x) ÷ (held + x). The smallest whole x that makes this at least 75% is x = ⌈(0.75 × held − attended) ÷ 0.25⌉. With 30 of 50, x = 30: 60 of 80 is exactly 75%.

How many classes can I miss and still have 75%?

If you miss y classes, attendance becomes attended ÷ (held + y). The largest whole y that keeps it at least 75% is ⌊attended ÷ 0.75 − held⌋. With 45 of 50 you can miss 10: 45 of 60 is exactly 75%.

Why does it say reaching 100% is impossible?

If the requirement is 100% and you have missed even one class, no number of future classes can bring you back to 100%.

Does it know my university's attendance rule?

No. Rules differ - some count lectures and labs separately, some excuse medical leave, some round 74.5% up. Enter the target your institution states and the classes it counts.

Related free tools

Percentage CalculatorX% of Y, percent of a total, increase/decrease, add or remove a percent, and marks.

GPA CalculatorSemester GPA and new CGPA from credits and grades, on 4.0, 5.0 or your own scale.

Grade CalculatorCurrent class grade from scores and weights, with a letter grade and weight check.

Final Grade CalculatorThe score you need on the final to reach your target grade, plus a what-if table.

Step-by-step guide: How to calculate attendance percentage →

Built and checked by Taimur Hassan Siddiqui, who has more than ten years in computer-science education. The formulas on this page are covered by an automated test suite, and the worked example on this page is one of its cases. Last updated 7 October 2026.