Attendance Calculator: Your % and Classes to Bunk (Free)

Your attendance percentage is classes attended ÷ classes held × 100. If you've attended 52 of 60 lectures, that's 86.67%. To know how many more you can miss and stay at or above 75%, divide attended classes by 0.75 and subtract the classes held so far: 52 ÷ 0.75 − 60 = 9.3, so 9 classes. The free percentage calculator works as an attendance calculator for the percentage; the two shortcuts below do the rest.

Many colleges and schools ask for 75% attendance before you can sit the end-semester or board exam. The exact rule, and whether medical leave or sports duty counts, varies by university, board and even department, so always check your own rulebook or ask the office.

Step 1: Find your attendance percentage

Formula: attended ÷ held × 100

• 52 attended out of 60 held: 52 ÷ 60 × 100 = 86.67%
• 45 out of 60: 75% exactly
• 38 out of 50: 76%
• 40 out of 60: 66.67%

In the calculator, use the second line, X is what percent of Y? Type the classes you attended first and the classes held second. The answer shows up to four decimal places, which matters when you're close to the line: 74.9% is still under 75%.

Count the same way the college does. Some count each lecture, some count each day, and labs often count as two or three periods. If your portal shows separate totals for theory and practicals, work them out separately, because many colleges apply the 75% rule to each.

Step 2: How many classes can I miss?

If you're above 75%, the question is how many classes you can skip before you drop below it.

Shortcut: classes you can miss = attended ÷ 0.75 − held, rounded down.

Example: 52 attended out of 60.

• 52 ÷ 0.75 = 69.33
• 69.33 − 60 = 9.33, rounded down to 9

Check it: after missing 9 more, you'd have 52 out of 69, which is 75.36%. Miss a 10th and it's 52 out of 70, or 74.29%, which is under.

Example: 38 out of 50 (76%). 38 ÷ 0.75 − 50 = 0.67, rounded down to 0. You're above 75%, but missing even one class takes you to 38 out of 51, about 74.5%. Being just over the line leaves no room.

This assumes no other classes happen while you're away. In practice, every class you do attend raises your buffer slightly, so plan from the numbers on the day.

Step 3: How many classes must I attend?

If you're below 75%, the question flips: how many classes in a row must you attend to get back to 75%?

Shortcut: classes needed = 3 × held − 4 × attended, rounded up.

Example: 40 attended out of 60 (66.67%).

• 3 × 60 = 180
• 4 × 40 = 160
• 180 − 160 = 20 classes in a row

Check it: 60 attended out of 80 is exactly 75%.

Example: 30 out of 50 (60%). 3 × 50 − 4 × 30 = 150 − 120 = 30 classes. That's 60 out of 80 again.

Where does the shortcut come from? You need (attended + n) ÷ (held + n) to be at least 0.75. Multiply out and you get n ≥ 3 × held − 4 × attended. For a different target, such as 80%, use this instead: n = (0.80 × held − attended) ÷ 0.20, rounded up.

Check whether there's time left

Knowing you need 20 classes is only half the answer. If there are 15 lectures left in the semester, 75% can't be reached by attendance alone, and it's time to talk to your teacher about condonation or medical certificates.

To count how many teaching days are left until the last working day, use the free date calculator. Its weekday count (Monday to Friday) is a good start; subtract holidays and exam days yourself, since it doesn't know your college calendar.

A quick table for 75%

Held	Attended	Attendance	Can miss	Must attend
40	36	90%	8	0
60	52	86.67%	9	0
60	45	75%	0	0
50	38	76%	0	0
60	40	66.67%	0	20
50	30	60%	0	30

The pattern: every class you miss costs more than you think when the total is small, and less as the semester goes on. Early absences hurt most.

Common mistakes

• Averaging subject percentages. If you have 90% in one subject with 20 classes and 60% in another with 80 classes, your overall attendance is not 75%. Add the attended classes (18 + 48 = 66) and the held classes (100), then divide: 66%.
• Forgetting the denominator grows. Missing a class doesn't just lose one from the top; it adds one to the bottom too. That's why the shortcuts divide by 0.75.
• Trusting a rounded portal figure. A portal showing "75%" might mean 74.6% rounded up. Work it out from the raw counts.

The same "part ÷ whole × 100" maths applies to exam scores; the guide to calculating percentage of marks covers totals across subjects, and the percentage formulas guide has the other common questions.

Check your attendance now

Type your attended and held classes into the second line of the free percentage calculator to see your attendance, then use the two shortcuts above for classes to miss or attend. It's free, needs no sign-up and works on your phone.