Skip to main content
FREE · INSTANT · BUNK CALCULATOR
Bunk Calculator
Find out exactly how many classes you can safely bunk — free, instant, and accurate. Enter your total classes, the classes you attended, and your target attendance, and see how many classes you can miss while staying above your target percentage.
- 100% free & instant results
- Runs entirely in your browser — we never store your data
- Built for students, teachers & schools
- Works for college, university & school attendance rules
ABOUT THIS TOOL
What Is a Bunk Calculator?
A bunk calculator tells you how many classes you can miss — “bunk” — without dropping below the attendance percentage your college, university, or school requires. It works from the numbers you already know: how many classes have been held, how many you attended, and the target percentage you need to meet.
Every class you bunk adds one to your total classes while your attended count stays the same, so your percentage falls a little with each miss. The calculator finds the largest number of bunks that still keeps you at or above your target — your safe bunks.
School, college, and university students all use a bunk calculator for the same reason: their attendance target is a hard line, not a rough idea. A single missed class lowers your percentage, and the cost of each miss grows as the term goes on. Early in a term, one absence can move your percentage far more than the same absence later, when many more classes have been held. Guessing how many classes you can miss is risky because the maths is not simple subtraction: you cannot take your current percentage, subtract your target, and treat the gap as free days. A wrong guess can turn into a shortage notice, a fine, or a barred exam hall, so check the exact number before you bunk.
Not sure where you stand today? Check your current figure first with the free Attendance Percentage Calculator, then use the bunk calculator below to plan your leave. For a full worked plan, read our bunk calculation guide.
PLAN AHEAD
Why Students Use a Bunk Calculator
A bunk calculator is not about skipping class for the sake of it. Students use it to plan, so a day off never turns into a problem at the end of the term.
- Plan leaves in advance. Festivals, family events, and travel all need days off. Check your safe bunks first and you will know whether the trip fits your attendance before you book anything.
- Protect the target percentage. Many colleges need 75% attendance before you can sit for exams. A quick check keeps every bunk inside the safe zone, so your target is never at risk.
- Avoid shortage notices. Attendance shortage can mean fines, warning letters, or barred exams. Knowing your exact limit keeps you clear of that list.
- Balance internships and exam prep. Internships, part-time work, and exam revision all compete for class hours. The calculator shows how many of those hours you can trade without slipping below target.
- Bunk planned, not on impulse. A planned bunk is a decision made with the numbers in front of you. An impulse bunk is a guess, and guesses are what cause shortage notices.
BUNK CALCULATOR
Bunk Calculator
Enter your total classes, the classes you attended, and your target attendance percentage. The calculator works out how many classes in a row you can safely bunk and stay at or above your target.
GETTING STARTED
How to Use the Bunk Calculator
Using this bunk calculator takes less than a minute. Follow these four steps and you will know exactly how many classes you can safely miss.
- Enter total classes. Type the number of classes held so far — every class conducted, whether you attended or not.
- Enter classes attended. Add only the classes you were actually present for, not ones you plan to attend.
- Choose your target. The calculator starts at 75%, but you can change it to 65%, 70%, 80%, or whatever your college, university, or school requires.
- Press calculate and read the result. Green means you have safe bunks available; the note underneath shows your attendance after bunking them. If the result is 0, you are already at your limit — attend the next classes instead.
THE MATH
The Bunk Calculator Formula
The bunk calculator runs on one formula. Each bunk adds a class to your total while your attended count stays the same, so the calculator finds the most bunks that still keep you at or above your target.
Say you have attended 80 out of 100 classes and your target is 75%. Divide 80 by 0.75 to get 106.67, then subtract the 100 classes held so far: 6.67, rounded down to 6 safe bunks.
Check it: after 6 bunks you stand at 80 ÷ 106 = 75.47%, still above 75%. One more bunk would leave you at 80 ÷ 107 = 74.77% — below target.
Planning across a whole term instead? Use the term formula: safe bunks = (total classes in term × (1 − target), rounded down) − classes already missed. A 120-class term at 75% allows 30 misses; with 12 already missed, 18 remain.
| Bunks | Total classes | Attendance |
|---|---|---|
| 0 | 100 | 80.00% |
| 3 | 103 | 77.67% |
| 6 | 106 | 75.47% |
| 7 | 107 | 74.77% |
BY TARGET
Safe Bunks at Common Targets
The target you choose changes everything. Here is what the same attendance record allows at five common targets. The worked example is a student who attended 90 out of 120 classes, which is 75.00% attendance right now.
| Target | Safe bunks | Attendance after bunking |
|---|---|---|
| 65% | 18 | 90 / 138 = 65.22% |
| 70% | 8 | 90 / 128 = 70.31% |
| 75% | 0 | 90 / 120 = 75.00% |
| 80% | 0 | Already below target |
| 85% | 0 | Already below target |
At 75%, this student has no safe bunks: 90 out of 120 is exactly 75.00%, so one more miss drops below target. At 80% and 85%, the target is already out of reach, so the answer is 0 and the student needs to attend classes in a row instead. If your college uses the 75% rule, read our guide to the 75% attendance rule in colleges to see how the rule works and what happens if you fall below it.
WORKED EXAMPLES
Bunk Calculator Examples
Five worked examples, checked with the bunk calculator above. Each row shows the most classes you can bunk in a row and the attendance you land on after bunking them.
| Total classes | Classes attended | Target | Safe bunks | Attendance after bunking |
|---|---|---|---|---|
| 100 | 80 | 75% | 6 | 80 ÷ 106 = 75.47% |
| 80 | 68 | 75% | 10 | 68 ÷ 90 = 75.56% |
| 120 | 96 | 75% | 8 | 96 ÷ 128 = 75.00% |
| 60 | 51 | 75% | 8 | 51 ÷ 68 = 75.00% |
| 100 | 85 | 80% | 6 | 85 ÷ 106 = 80.19% |
Figures are rounded down — one more bunk in any row would drop you below target. For more worked numbers, read how many classes can I miss.
REAL SCHEDULES
Bunk Calculator Examples for Real Schedules
Three students, three situations. Each example uses the same formula, with class numbers a student might actually have.
Already below target
Inputs: 82 classes attended out of 110 held, target 75%.
Working: 82 divided by 0.75 is 109.33. Subtract 110 to get minus 0.67, so there are no safe bunks: the result cannot go below 0.
Answer: 0 safe bunks. This student is at 74.55% right now, already below target. Attend 2 classes in a row and the record becomes 84 out of 112, which is exactly 75.00%.
Comfortably above target
Inputs: 145 classes attended out of 180 held, target 75%.
Working: 145 divided by 0.75 is 193.33. Subtract 180 to get 13.33, which rounds down to 13 safe bunks.
Answer: 13 safe bunks. After 13 bunks the record is 145 out of 193, which is 75.13%. One more bunk would drop it to 74.74%.
One class of room
Inputs: 76 classes attended out of 100 held, target 75%.
Working: 76 divided by 0.75 is 101.33. Subtract 100 to get 1.33, which rounds down to 1 safe bunk.
Answer: 1 safe bunk. After that bunk the record is 76 out of 101, which is 75.25%. One more bunk would drop it to 74.51%.
BUNK SMART
Smart Bunking Rules
Safe bunks are a limit, not a target to use up. These five rules keep a good number safe all term.
- Keep a buffer of 2 to 3%. Never bunk down to your exact target. Leave 2 to 3 percentage points of room for a sick day or a class that still counts against you.
- Never bunk two heavy subjects on the same day. Missing one hard subject is a setback. Missing two in one day can leave a gap that takes weeks to close.
- Re-check after every absence. Your safe bunks change after each missed class, so run the calculator again before the next bunk, using the new totals.
- Know your exact rule. Some colleges count 75%, others 80%, and some count practicals separately. Check your handbook so you plan against the real rule.
- Bunk planned, not on impulse. Decide the day before, with the numbers in front of you. A bunk taken on a whim is the one that usually breaks the target.
KNOW THE LIMIT
When You Should NOT Bunk
There are days when the calculator says you can bunk and the answer should still be no.
- You are below target. If the calculator shows 0, there is no safe bunk. Attend, and climb back above the line first.
- Practical and lab classes. Practicals are often graded on the day and cannot be made up later, so a missed lab costs more than a missed lecture.
- Exam weeks. The week before exams is when teachers revise the most important topics. A bunk then costs revision time, not just attendance.
- The first week of term. The first week sets the pattern: timetables, groups, and first assignments. Miss it and you start the term behind.
COMMON QUESTIONS
Bunk Calculator FAQs
How many classes can I bunk and still keep 75%?
With 80 classes attended out of 100 held, you can bunk 6 classes in a row and still stay at 75% or above — 80 ÷ 106 = 75.47%. In general, safe bunks = classes attended ÷ your target − total classes, rounded down. More worked numbers are in our guide to how many classes can I miss.
What is a safe bunk?
A safe bunk is a class you can miss while keeping your attendance at or above your target percentage. Each bunk adds one class to your total while your attended count stays the same, so your percentage falls a little with every bunk — the calculator finds how many you can afford before you cross your target.
What if my attendance is already below my target?
Then you have no safe bunks right now — the calculator will show 0. You need to attend classes in a row, with no further misses, to climb back to your target. Check your current figure on the Attendance Percentage Calculator first, then plan from there.
Does bunking one class always cost the same?
No. Early in a term, each class is worth more to your percentage than it is later, once the total class count is higher. Missing classes early in a term hurts far more than missing them later, which is why a running calculation — not a one-time estimate — is what actually keeps you safe.
Is this bunk calculator free and accurate?
It is completely free with no sign-up, and it runs entirely in your browser — we never store your data. The maths is exact, but the result is only as accurate as the numbers you enter; your official register is the final record.
Is bunking the same as attendance shortage?
No. Bunking is one choice to miss a class. Attendance shortage is the result of missing too many: your percentage falls below the required level, and your college may stop you from sitting for exams. A bunk calculator helps you bunk without reaching shortage.
Does the calculator work for 75% rule colleges?
Yes. The calculator starts at 75% because that is the most common college rule. Enter 75 as your target and it gives your safe bunks for that rule. If your college needs a different target, change the target box to match it.
How often should I re-check my safe bunks?
After every absence, and at least once a week during term. Each missed class changes your totals, so a number that was safe last week may not be safe now. Re-check before every planned bunk.
Does it work for school students too?
Yes. The maths is the same for school, college, and university. Enter your total classes, the classes you attended, and the target your school sets, and the calculator works out your safe bunks the same way.
Latest Articles
Application to the Principal: Format & Samples
Morning assembly is about to begin, and a student is standing outside the principal’s office with a folded piece of paper in hand. The student
Study Certificate: Format, Uses & How to Get One
A study certificate is an official document issued by a school, college, or university that confirms a student studied at that institution for a stated
Gap Certificate: Format, Affidavit & How to Get One
What Is a Gap Certificate? A gap certificate is a signed declaration that explains a break in a student’s education. It states, in plain words,
Oklahoma Report Cards: Attendance Up, Graduation Down
Oklahoma’s public schools received their annual report cards last week, and the two numbers that matter most to families moved in opposite directions. Attendance improved.
FMGE October 2026 Result: NBEMS Sets November 30 Deadline
The wait for the FMGE October 2026 result now has a date attached to it. The National Board of Examinations in Medical Sciences has said
Camden Schools Aim to Halve Chronic Absenteeism by 2027
Camden City School District has set itself one of the clearest attendance targets in the country: cut its chronic absenteeism rate in half by June
