Instructor-to-Student Ratio Calculator
Determine the maximum and recommended instructor-to-student ratios for scuba courses based on certification level, water conditions, and assistant availability.
Inputs
Results
Max students per instructor
4
Recommended ratio
3
How to Use This Calculator
- Select the course level being taught (open water, advanced, rescue, or specialty).
- Choose the water conditions: ideal, moderate, or challenging (cold/current/low visibility).
- Indicate whether a certified divemaster or assistant instructor is present.
- Enter the total number of students enrolled in the course.
- Select the students' experience level: brand new, some confined water experience, or already certified.
- Read Max Students per Instructor and Instructors Needed to staff the course in compliance with agency standards.
What each input means
- Course level
- 0 = Confined/pool, 1 = Open Water, 2 = Advanced/Specialty, 3 = Rescue, 4 = Technical/Deco.
- Water conditions
- 0 = Ideal (calm, warm, good viz), 1 = Moderate, 2 = Challenging (cold, current, low viz).
- Certified assistant?
- 0 = No, 1 = Yes (divemaster or assistant instructor present).
- Total students
- Number of students to be trained.
- Student experience
- 0 = Brand new, 1 = Some pool/confined experience, 2 = Already certified (continuing education).
What each result means
- Max students per instructor
- Maximum allowed student-to-instructor ratio for the scenario.
- Recommended ratio
- Conservative recommended ratio (~75% of maximum).
- Instructors needed
- Minimum instructors required for your student count.
- Recommended instructors
- Recommended number of instructors for optimal training quality.
- Assistants needed
- Number of divemasters or assistant instructors to support.
- Actual ratio
- Effective student-to-staff ratio with all staff counted.
- Training quality score
- Estimated training quality score (0-100). Higher is better.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersCourse level = 1, Water conditions = 0, Certified assistant? = 0, Total students = 6 = 5 input(s) provided
- Calculate Max students per instructorMax students per instructor4 = 4
- Calculate Recommended ratioRecommended ratio3 = 3
- Calculate Instructors neededInstructors needed2 = 2
- Calculate Recommended instructorsRecommended instructors2 = 2
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.
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