Passing the plumbing exam can feel like a big hill to climb—but it doesn’t have to. With the right approach and a little math know-how, you can break down even the trickiest questions and walk into your exam with confidence. In this post, Roger Wakefield shares his favorite study tools and techniques, plus a few test-style questions you’ll want to master.
Use the Right Study Guide—and Read It the Smart Way
Roger starts with one of his favorite tools: the UPC Study Guide. Here’s a trick—he marks all the right answers in advance and reads it like a book. That way, he’s not wasting brain space on the wrong choices. By focusing only on the correct answers, you reinforce what you’ll actually need to know.
Tip: Don’t just memorize—understand. Read the guide out loud or explain the answers to yourself like you’re teaching them to someone else.
Common Plumbing Math Made Easy
Let’s look at a few questions you’re likely to face.
Question 1: How many cubic inches in a cubic foot?
Visualize it like a box: 12 inches on all sides.
12 x 12 = 144 (square inches in a face)
144 x 12 = 1,728 cubic inches in a cubic foot
Knowing this can help you when calculating tank sizes, weights, or pressure.
Bonus Tip:
One cubic foot holds 7.48 gallons of water.
One gallon weighs 8.34 pounds.
So a full cubic foot weighs over 62 pounds. That’s crucial when mounting tanks or working on rooftops.
Water Column Pressure—Understand PSI
Another question that trips people up is pressure from a column of water.
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1 foot of water = 0.434 PSI
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1 inch of water = 0.036 PSI
If you’re trying to find the pressure from, say, an 86-foot tall pipe, just multiply:
86 x 0.434 = 37.32 PSI
Why this matters: If you know how tall a pipe is or how far water has to rise, you can estimate pressure at any point in the system.
Offsets Made Simple
Let’s say you have two water pipes 4 feet apart center-to-center, and you need to connect them with 45-degree fittings. Use the multiplier 1.41 to get the length of your diagonal offset.
4 x 1.41 = 5.64 feet (about 5 feet 7 inches)
Pro Tip: Always subtract the fitting makeup from your final cut length to get it right.
Roger’s Pro Study Tip
One of the hardest questions Roger remembers actually helped him understand, not just memorize. That’s the difference between just passing and really being a skilled plumber. When you know how to break things down and apply real math, you can work smarter in the field, not just in the exam room.
Final Thoughts
Whether you’re prepping for your journeyman exam or just brushing up on plumbing basics, math is your friend. From pressure calculations to offsets and volumes, mastering a few formulas will set you apart.
If you’re struggling to figure out how to study, follow Roger’s lead:
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Mark the right answers
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Read your study guide like a story
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Practice questions by drawing them out
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Memorize core formulas and practice using them
And remember, you’re not just studying for a test. You’re learning to be a professional in a trade that keeps the world running.
