What physics topics are covered in the PADI IDC exam?

The PADI IDC physics exam covers eight topic areas: pressure fundamentals (absolute, gauge, ATA, bar), depth-to-depth calculations, density at depth, partial pressure (Dalton's Law), buoyancy states, lift bag calculations, fresh water physics, and general knowledge including Henry's Law, Charles's Law, sound underwater, heat loss, and colour absorption.

What is the best order to study PADI IDC dive physics?

Start with Pressure Fundamentals and the 3-step method — every calculation topic builds on this foundation. Then work through depth-to-depth calculations, density, and partial pressure before moving to buoyancy and lift bags. Fresh water physics and general knowledge can be studied last as standalone topics.

How do you pass the PADI IDC physics exam?

Master the 3-step pressure calculation method first — it applies to the majority of exam questions. For each topic, understand the core logic (why multiply or divide) rather than memorising formulas. Worked examples on each topic page show exactly how to approach every question type in the exam.

Do PADI Divemaster candidates sit the same physics exam as IDC students?

Yes. PADI Divemaster and IDC candidates sit the same set of dive theory exams, including physics. The passing standard is 75% for Divemaster and 75% for IDC, with a higher combined standard required at the Instructor Examination.

Dive Physics — PADI IDC & Divemaster Study Notes

The PADI Divemaster and IDC physics exam covers eight topic areas. These pages work through each one — core concept first, then worked examples that match the exact question types in the exam. Start with Pressure Fundamentals if you are new to the material. Every other topic builds on the pressure foundation.

Work through the topics in order — each one builds on the last.

Topic 1

Pressure Fundamentals

Absolute & gauge pressure, ATA, bar, the 3-step method, refraction

Topic 2

Depth Calculations

Moving between depths, 3-step-twice method, first depth & second depth

Topic 3

Density

Gas density at depth, pressure and density proportional, eight worked examples

Topic 4

Partial Pressure

Dalton's Law, PPO₂ and PPN₂ at depth, nitrox, contaminated tanks

Topic 5

Buoyancy

Positive, negative, neutral buoyancy states, salt water vs fresh water

Topic 6

Lift Bag Calculations

Unknown weight, unknown volume, worked examples for the exam

Topic 7

Fresh Water Physics

Fresh water pressure calculations, 1.00 vs 1.03 kg/L, gauge pressure in fresh water

Topic 8

General Knowledge

Sound, heat loss, colour absorption, Henry's Law, Charles's Law

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