Trades

Reference math for the jobsite. Open, type, copy, close.

What this is

This is the trades section of HandyConvert — reference math for the people who actually swing the hammer, pull the wire, or set the duct. Carpentry math in inches and fractions, electrical math in voltage and gauge, HVAC math in BTUs and tons, plumbing math in pipe sizes and flow. Bilingual English and French. Free, no signup, no install, no app store.

The renovation calculators — paint, deck, drywall, tile, insulation — live on our companion site RenoSheets. RenoSheets handles the project layer (full materials list, Kanban planner). HandyConvert handles the quick conversions you need on the way to the cut.

Tools

Carpentry

Inch fraction calculator → Add, subtract, multiply, divide fractions and mixed numbers. Returns simplified fraction, decimal inches, and millimetres.

Board feet calculator Soon Calculate board feet from thickness × width × length × quantity. Returns total board feet and total cost at a per-bf rate.

Roof pitch and angle converter Soon Convert between pitch (rise per 12), degrees, and percent grade, with rafter length for a given run.

Lumber nominal vs actual Soon Look up actual finished dimensions for 1×, 2×, 4×, 6× lumber sizes — the numbers that matter when stacking.

Electrical (reference)

Voltage drop calculator Soon Voltage drop across a copper or aluminium conductor at a given gauge, length, and load. Single phase and three phase.

AWG to mm² converter Soon Convert American Wire Gauge to metric cross-section, with a reference table of common gauges and their ampacity.

kVA, kW, BHP converter Soon Switch between apparent power, real power, and horsepower for a given power factor.

HVAC

BTU, ton, kW converter Soon Switch between BTU/hr, tons of refrigeration, and kilowatts for heating and cooling sizing.

CFM and static pressure Soon Airflow conversions for residential and light commercial duct sizing reference.

R-value and RSI converter Soon Convert between imperial R-value and metric RSI, with reference values by climate zone.

Plumbing

Pipe size converter Soon Nominal pipe size to outside diameter, with metric DN equivalent and common Schedule 40 inside diameters.

Flow rate converter Soon Convert between US gallons per minute, litres per minute, and cubic metres per hour.

Drain slope calculator Soon Calculate drop over run for a target slope (1/4″ per foot, 1/8″ per foot, or custom).

Why a website and not an app

You probably have one or two trades apps on your phone you use every day. Everything else is one Google search away. That is the moment we are built for — the look it up, get the number, close the tab moment. No download, no account, no app permissions, no notification spam. The URL of any calculation can be texted, emailed, or pinned to a forum thread, and the recipient sees exactly what you saw — useful for sharing a cut list with an apprentice or showing a customer your math.

Every tool here is mobile-first, with 56-pixel tap targets that work through work gloves, a high-contrast layout that reads in direct sun, and tabular monospace numerals so the digits do not jitter as you type. Each result page is also printable and the inputs are encoded in the URL for sharing.

Reference only — not a design tool

The tools here are reference utilities. They are not engineering design software. Decisions that affect life safety — structural load, electrical code compliance for permitted work, gas piping, pressure vessels, anything load-bearing — belong to a licensed engineer, master electrician, or inspector working from the local code. We will help you check a calculation; we will not replace a credentialed pro.

Where we cite a code or standard (NEC, ASHRAE, NPC, CSA, NRC Metric Commission), we link to the official source so you can verify the rule. Methodology for every calculator is documented on a separate Methodology page.