NCEES PE exam prep
Pass your PE exam.
Walk in ready, walk out done — prep built for the exact exam you're sitting.
7 days free · no card · cancel anytime.
- 1,000+ exam-real problems
- Grounded AI tutor
- Full-length 8-hour mocks
- Handbook-cited solutions
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.
Worked solution
Weight by mass flow, not 50/50 — the outdoor air is a quarter of the stream:
The AI tutor
Meet Castor — the tutor that's already worked the problem
Every CastorPrep problem ships with a worked solution written and reviewed before it goes live. Castor is grounded in that solution — so when you're stuck, it doesn't guess. It knows the exact step where your answer diverged, and it cites the Handbook section you'd need on exam day.
And it works both sides of the answer: stuck before you submit, Castor coaches — it probes your setup and gives one nudge at a time, never the letter. After you answer, it debriefs your exact miss.
No generic AI answers: Castor works from the verified solution and the Handbook — not from whatever the internet thinks.
Castor— AI tutor
On a live problem: cooling coil, 6,500 cfm — total load in tons.
A real exchange with Castor, on a real problem from the bank.
Full-length mocks
Rehearse the full eight hours.
80 questions, 8 hours of timed testing, per depth — pause and resume, so a mock fits your real schedule.
- 80 questions, 8 hours, timed
- Pause & resume — the clock holds at 8 hours
- Pace + score + weak-area breakdown after
8 h working time · pauses don't burn the clock
An ideal Rankine cycle takes in 2,640 kJ/kg in the boiler and rejects 1,620 kJ/kg in the condenser. Determine the cycle's thermal efficiency.
The exam
Built for the exam you're sitting.
PE Mechanical
Exam overview →Heaviest on psychrometrics (~¼), plus equipment and heat transfer.
Six areas on a mechanics-of-materials spine — fatigue, the broadest scope.
Highest first-time pass — but power cycles and compressible flow are the traps.
PE Electrical: Power
Coming soonOne of the fastest-growing PE exams — opening soon on CastorPrep.
Still deciding which to sit? Which depth should you take? →
How it works
Quality you can trace.
Every CastorPrep problem is built to a standard — mapped to the exam, original, solved and checked, and Handbook-cited. The AI tutor teaches straight from that verified work, so the help you get on every problem is grounded and reliable.
NCEES Blueprint
Mapped to the real exam
Pinned to an NCEES area and its exam weight, matched to what the real exam tests.
Original
Original to CastorPrep
Purpose-built to exercise the exact engineering methods the PE Mechanical exam tests.
Worked Solution
Solved and checked
A full step-by-step solution — every answer and distractor recomputed before it ships.
Handbook Ref
Cited to the Handbook
Tied to the exact NCEES Reference Handbook section the method comes from.
Grounded AI
Help on every problem
Ask why you're wrong, get a hint, or have a concept explained — figures and exhibits too.
NCEES Blueprint
Mapped to the real exam
Pinned to an NCEES area and its exam weight, matched to what the real exam tests.
Original
Original to CastorPrep
Purpose-built to exercise the exact engineering methods the PE Mechanical exam tests.
Worked Solution
Solved and checked
A full step-by-step solution — every answer and distractor recomputed before it ships.
Handbook Ref
Cited to the Handbook
Tied to the exact NCEES Reference Handbook section the method comes from.
Grounded AI
Help on every problem
Ask why you're wrong, get a hint, or have a concept explained — figures and exhibits too.
The tutor is the payoff of that pipeline — How the tutor works →
Start free
Ready when you are.
Seven days, full access — the full bank of exam-real problems with a grounded AI tutor on every one, full-length timed mocks, and a diagnostic to aim your reps. No card to start, cancel anytime.
7 days free · no card · cancel anytime.