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Attendance Calculator (75% Rule)

Most schools, colleges and boards require at least 75% attendance to sit exams. Enter the classes held and attended to see your attendance percentage — and exactly how many classes you can safely miss, or how many you must attend in a row to get back above the limit.

%
Your attendance
90%
Classes you can miss
10

You are above 75%. You can miss up to 10 of the next classes and still be eligible.

Step-by-step solution
  1. Current attendance = (45 ÷ 50) × 100 = 90%
  2. To stay at 75%: 45 ÷ (50 + y) ≥ 0.75
  3. y ≤ 45 ÷ 0.75 − 50 = 10 → you can miss 10 classes

How to use the attendance calculator

  1. Enter the total number of classes held so far and how many you attended.
  2. Set the required attendance — 75% is the default for most colleges and CBSE.
  3. See your current percentage and the number of classes you can miss or must attend.

Formulas

Attendance %(Classes attended ÷ Classes held) × 100
Classes you can missfloor(Attended ÷ Required − Held)
Required as a decimal, e.g. 0.75.
Classes you must attendceil((Required × Held − Attended) ÷ (1 − Required))

Solved examples

Example 1: 45 classes attended out of 50. How many can you miss and stay at 75%?

  • 45 ÷ 0.75 − 50 = 60 − 50

Answer: 10 classes (45/60 = 75%)

Example 2: 30 classes attended out of 50. How many must you attend to reach 75%?

  • (0.75 × 50 − 30) ÷ 0.25 = 7.5 ÷ 0.25

Answer: 30 classes in a row (60/80 = 75%)

Why 75% matters

CBSE requires 75% attendance for students to appear in board exams, with relaxation only in cases such as medical emergencies or participation in national-level events, backed by documents. Most universities and AICTE-affiliated colleges follow a similar 75% rule and can stop students from writing semester exams if they fall short.

The rule is usually applied subject-wise in college, so check each subject separately rather than your overall attendance.

Plan ahead, not at the end of term

Because every missed class also increases the total, falling below 75% takes several classes to recover from. For example, dropping from 30/40 (75%) to 30/44 (68%) takes just four absences, but getting back to 75% then needs 12 consecutive classes. Checking early keeps you safe.

Frequently asked questions

How do I calculate my attendance percentage?

Divide the number of classes you attended by the number held, then multiply by 100. 42 out of 50 classes = 84%.

How many classes can I miss and keep 75% attendance?

Divide your attended classes by 0.75 and subtract the classes held so far; round down. The calculator does this instantly.

Is 75% attendance compulsory for CBSE board exams?

Yes. CBSE requires 75% attendance to appear in board exams, with limited relaxation for documented reasons such as serious illness.

Does this work for a different requirement like 80% or 85%?

Yes. Change the required attendance field to any percentage your school or college uses.

Does the calculator count future holidays?

No. It assumes every future class is held. Use it again as the term goes on for the most accurate result.

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