Example 1
- Unit: classes
- Total 100, present 80, threshold 75
80%, still allowed to miss 5
How many more can I miss at 80 out of 100 and 75%? 5, because the absence limit is 25 and 20 are already entered.
Attendance Calculator
The calculator divides the number of attended classes by the total and multiplies by 100. 80 present out of 100 classes is 80%. At a 75% threshold you may have at most 25 absences, so after 20 you can still miss 5.
This is not a school SIS and not a promotion decision. You type the threshold. A plain percentage of a number, without attendance, is on the percentage of a number page.
Result
Enter the total and the number present. The attendance percentage appears here.
How it works
The calculator divides the number present by the total number of classes and multiplies by 100. 80 present out of 100 classes is 80%. 32 out of 40 is 80%. 28 out of 40 is 70%.
The class total is fixed. At a 75% threshold on 100 classes you may have at most 25 absences, because 75 present is the minimum. After 20 absences, 5 remain. The calculator does not add 6 classes beyond that 100.
When the result is below the threshold, the calculator counts how many present classes that same plan still needs. At 28 present and 12 absences out of 40, 30 present are required. That is unreachable, because the plan is already filled.
The default threshold of 75% is not a university statute. Many attendance tools use that number, so it starts in the field. If your rule is 80% or 90%, type that value.
You enter present and absences separately. Their sum cannot exceed the total. The rest are classes not held yet. The classes and days switch does not change the formula, only the labels.
This is not a gradebook. The numbers stay in the browser. A percentage of one number, without a class total, is on the percentage-of-a-number page.
Formula
attendance % = present / total × 100
Minimum present = ceil(total × threshold / 100). Absence limit = total − that minimum. Still allowed to miss = the limit minus absences already entered, with no classes beyond that total.
How to use it
- Choose classes or days. The formula stays the same.
- Enter the total, present, and absences. 80 present and 20 absences out of 100 classes is 80%.
- Set a threshold, for example 75. On 100 classes the absence limit is 25, so after 20 absences you can still miss 5.
- If you are below the threshold and the plan is already filled, the result says the threshold is unreachable. That is the case at 28 present and 12 absences out of 40.
- This is not a SIS. Compare the result with your own rule, not with the default field.
80% at 80 out of 100
The calculator divides present by the total and multiplies by 100. 80 out of 100 is 80%.
- %
- Attendance: present / total × 100. 80 out of 100 is 80. 28 out of 40 is 70.
- threshold
- The number you type. The default on this page is 75. It is not an automatic university rule.
- miss
- Further absences that still fit the limit on the total you typed. At 80 out of 100 and 75%, 5 remain.
Examples
Example 2
- Unit: classes
- Total 40, present 32, threshold 75
80%, still allowed to miss 2
32 / 40 × 100 is 80%. The absence limit is 10, and 8 are already entered, so 2 remain.
Example 3
- Unit: classes
- Total 40, present 28, threshold 75
70%, threshold unreachable
28 / 40 × 100 is 70%. With 12 absences the limit of 10 is already passed, so 75% cannot be reached in this set.
Related calculators
Frequently asked questions
What is attendance at 80 present out of 100 classes?
80%. The calculator divides 80 by 100 and multiplies by 100. At a 75% threshold you may have at most 25 absences, so with 20 already recorded you can still miss 5.
How many more classes can I miss?
As many as still fit the absence limit on the total you typed. At 100 classes and 75%, that limit is 25. After 20 absences, 5 remain. The calculator does not add classes beyond that 100.
What if I am already below the threshold?
The calculator shows how many more present classes that same total still needs. At 28 present and 12 absences out of 40, a 75% threshold needs 30 present. That is unreachable, because the plan is already filled.
Is 75% a university rule?
No. 75% is only the default threshold on this page, because many attendance tools use it. Type the rule that applies to you.
Does this read a school SIS?
No. The calculator uses only the numbers you enter. It does not open a gradebook and it does not record a promotion decision.
Do classes and days use different math?
No. The formula is the same. The switch only changes the labels in the result.
How does the absences field work?
You enter it separately. Present plus absences cannot exceed the total. The rest are classes that have not been held yet.
Why can 100% be unreachable?
Because earlier absences stay in the denominator. 99 present out of 100 never returns to 100%, even if you miss nothing else.
Does a comma in 33,5 work like a period?
Yes. 33,5 and 33.5 are the same number. Avoid thousand separators inside the number.
How is this different from percentage of a number?
Percentage of a number finds a part of one value. Here the denominator is the class total, and the result also answers how many more you can miss.
Sources
Attendance is the ratio of present classes to the total, written as a percent.
Page updated in 2026.