NCEES PE exam prep

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Prep for your PE exam with CastorPrep: 1,000+ exam-real problems per exam, built to the NCEES specification, each with a worked solution and an AI tutor grounded in it.

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Built to the current NCEES specifications

PE Mechanical

Spec effective October 2025

PE Electrical: Power

Spec effective October 2025

PE Civil: Water Resources & Environmental · Transportation

Spec effective April 2024

1,000+
exam-real problems per exam
AI tutor
grounded in each problem’s worked solution
5 mocks
per exam: timed, 8 hours, 80 questions
Cited
the NCEES Handbook section wherever the method has one

The platform

From first problem to exam day.

Exam-real practice with a worked solution on every problem, a tutor grounded in those solutions, a diagnostic that ranks your weak areas, and full-length mocks that run the real eight hours.

Exam-real problems, solved step by step.

Written to your exam's NCEES specification, area by area, and each one comes with a worked solution that shows the method, not just the number.

  • A worked solution on every problem
  • The Handbook section where the method has one
  • All five of the exam's item formats, from fill-in to drag-and-drop
Practice · HVAC & Refrigeration
Exam format
Easy6 min · USCS

4,000 cfm of outdoor air at 95°F mixes with 12,000 cfm of return air at 75°F. Find the mixed-air dry-bulb temperature.

A.77.0 °F
B.80.0 °F✓
C.85.0 °F

✓ Correct. The correct answer is B.

Worked solution

Weight by mass flow, not 50/50 — the outdoor air is a quarter of the stream:

T = \frac{4{,}000 \times 95 + 12{,}000 \times 75}{16{,}000} = \mathbf{80.0\ ^\circ F}
the adiabatic mixing equation · §9.2.3 Adiabatic Mixing of Two Moist Airstreams (starts p. 481)

The exam

Built for the exam you're sitting.

Still deciding which to sit?PE Mechanical exams →PE Electrical exams →PE Civil exams →

PE Mechanical

HVAC & Refrigeration

Equipment and components carry the most weight, then distribution systems, then loads and psychrometrics.

First-time pass rate

69–71%

PE Mechanical

Machine Design & Materials

Six areas on a mechanics-of-materials spine, with components and assemblies close behind.

First-time pass rate

61–64%

PE Mechanical

Thermal & Fluid Systems

Thermal-fluid principles carry the most weight, with fluid equipment and power systems close behind.

First-time pass rate

70–71%

PE Electrical: Power

Power

Safety and the NEC, circuit analysis and protection carry the most weight across its nine areas.

First-time pass rate

58%

PE Civil

Water Resources & Environmental

Hydraulics, hydrology and treatment — plus sitework, the largest single area.

First-time pass rate

71%

PE Civil

Transportation

Traffic, geometry and signals, with traffic engineering the largest single area.

First-time pass rate

61%

Our standard

Quality you can trace.

Every CastorPrep problem is built to a standard — mapped to the exam, original, solved and checked. The AI tutor teaches straight from those worked solutions, so its help is grounded in them.

  1. 01 — NCEES Blueprint

    Mapped to the real exam

    Pinned to an NCEES area and its exam weight, matched to what the real exam tests.

  2. 02 — Original

    Original to CastorPrep

    Purpose-built to exercise the exact engineering methods your exam tests.

  3. 03 — Worked Solution

    Solved and checked

    A step-by-step solution — every answer and distractor recomputed before it ships.

  4. 04 — Handbook Ref

    Cited by section

    Tied to the exact NCEES Reference Handbook section the method comes from, wherever the method has one.

  5. 05 — Grounded AI

    Grounded help

    Ask why you're wrong, get a hint, or have a concept explained — figures and exhibits too.

Ready when you are.

Your exam’s first chapter is free with an account — every problem in it with a worked solution, and Castor to walk any one you miss. No card, and it doesn’t expire.

Start with a free chapter