It is a planning tool, not an oracle. Use it to compare strategies - more study hours vs tutoring vs practice papers - and to spot when the realistic chance is too low to rely on a single attempt. Pair it with the Study Hours Calculator to size the study block behind the inputs.
Calculator
Formula used
P(pass) = Φ((expected − pass) ÷ σ) · expected = past mean + studyEffect
How to use the Exam Pass Probability Calculator
- Enter your recent average score and how much it usually varies.
- Type the pass mark and how many study hours you have left.
- Adjust the score lift per hour to match your study method.
- Read the pass chance and the table of probabilities by hours.
About this tool
The Exam Pass Probability Calculator is built for speed and accuracy: every calculation runs in your browser, so your data never leaves your device and the result updates as you type. It works equally well on a phone, a tablet or a desktop, and it is free to use as many times as you like.
Common use cases
- Comparing "more study" vs "tutoring" strategies.
- Deciding whether to defer an exam.
- Estimating a target for revision.
- Building a quick risk score before a final.
Tips for the best result
- Use the latest figures you have - even a small change in rate or term can shift the outcome by hundreds.
- For annual figures, divide by 12 to get a monthly number you can compare with the result.
- Bookmark this page and revisit the calculation as the inputs change.
Frequently asked questions
How do I estimate the standard deviation?
Use 4-10 points for a typical student. Take 5-10 past test scores, subtract the mean from each, square, average, and take the square root - or just use a rough value; the model is robust to small errors.
What is a realistic score lift per hour?
Focused individual study tends to lift scores by 0.4-0.8 points per hour for material the student has seen before. Tutoring or active recall sessions can push that to 1-1.5 points per hour.
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