Trade guides & how-tos
Clear, plain-English answers to the questions tradespeople, contractors, inspectors and homeowners actually search — how to size it, calculate it, and what the code asks for. Every guide cites its sources and links to a free calculator.
- How much concrete do I need?How much concrete do I need? Enter length, width and thickness — get cubic yards, metres and bags.
- How much gravel do I need?How much gravel do I need? Enter length, width and depth — get tons, cubic yards and tonnes for gravel, road base or sand.
- How much asphalt do I need?How much asphalt do I need? Enter length, width and thickness — get the tons (and tonnes) of hot-mix asphalt to order for a driveway, path or car park.
- How to calculate board feetHow many board feet do you have? Enter thickness, width, length and quantity — get the total board footage of lumber, plus the volume in cubic feet or metres.
- How to calculate roof pitchEnter rise and run — get the pitch (x:12), the roof angle, grade %, slope factor and rafter length.
- How to calculate roofing materialsHow much roofing do I need? Enter your roof footprint and pitch — get the area, the roofing squares and how many bundles of shingles to order.
- How to calculate stairsEnter your floor-to-floor rise — get the number of risers, riser height, run, stringer length and angle.
- How to calculate voltage dropWill my wire drop too much voltage? Enter the current, run length and wire size — get the % drop checked against the 3% / 5% guideline, in AWG or mm², copper or aluminium.
- How to calculate GPM (water flow rate)Measure your water flow rate — time a container filling, get gallons per minute.
- PEX vs copper pipeCost, lifespan, where each wins, and which to use — a plain-English comparison.
How these guides are written
Each guide starts from the questions people genuinely ask about a calculation — pulled from real search data, not invented — and answers them in order of how often they're asked. The structure is deliberate: the direct answer first, then the method step by step, then a worked example with real numbers you can follow on paper, then the follow-up questions. Where a building-code rule applies, the guide names the code and edition; where something is a rule of thumb rather than a legal requirement, it says so plainly.
Every guide pairs with a free calculator that does the same math instantly, so you can read the method once and then use the tool for every job after that. Guides are reviewed when codes change and carry a "last reviewed" date — if you spot something out of date, the contact page is the fastest way to tell us.