Free trade calculators
Simple calculators for apprentices and journeypersons. They run in your browser and don't collect any data.
For learning only. Check your code book. These calculators are study aids, not design tools. Always follow the code that applies where you work, the manufacturer's instructions and your supervisor. Nothing you type is sent to us or anyone else.
Updated: Oct 2026.
Apprenticeship hours tracker
Log your on-the-job and in-school hours and see your progress toward your trade's total.
Open →Ohm's law and voltage drop calculator
Solve for volts, amps, ohms or watts, and estimate voltage drop on a run.
Open →Stair and rafter calculator
Work out risers, treads and stringer length, or common rafter length from run and pitch.
Open →Trade unit converter
Convert length, area, volume, pressure, power, flow, temperature and more, plus fractional inches to millimetres.
Open →Looking for books and tools to buy? See our Books & Tools picks.
FAQ
Are these calculators free?
Yes. They're free, there's no sign-up, and nothing you type is sent to us or anyone else.
Can I use these results on the job?
Use them for learning and to check your own math. Always follow the code that applies where you work, the manufacturer's instructions and your supervisor.
Where are my apprenticeship hours saved?
Only in your own browser, using local storage on that device. Clearing your browser data deletes them, so export a CSV regularly. Your official hours are the ones your apprenticeship authority records.
Sources
- NIST Special Publication 811, Appendix B.8 — Factors for units listed alphabetically (opens in a new tab)
- NIST — SI units (opens in a new tab)
- National Research Council Canada — National Building Code of Canada 2020 (opens in a new tab)
- Ellis Chart — apprenticeship hours by trade and province (ellischart.ca) (opens in a new tab)