FieldDojo: Trade Calculators

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About this app

FieldDojo puts 57 code-referenced trade calculators in one fast, offline app. Built for electricians, plumbers, HVAC technicians, framers, concrete crews, and general contractors who need answers on the job — not a sign-up form.

Every calculator is free and runs on-device. No account needed to calculate. Switch between imperial and metric with one tap. Every result is saved to history and shareable as text in one tap. FieldDojo Pro adds formatted PDF reports, cloud sync, unlimited history, and unlimited projects.

▸ ELECTRICAL (14, NEC-referenced)
• Wire size by amperage (NEC 310.16)
• Voltage drop (and reverse: wire size for max drop)
• Conduit fill per NEC Chapter 9
• Residential load calculation (NEC 220)
• Breaker size, motor FLA, ground wire, transformer kVA, and more

▸ PLUMBING (9)
• Pipe sizing by fixture units (UPC/IPC)
• Flow rate (Hazen-Williams)
• Drainage slope and pitch
• Water heater sizing
• Gas pipe size (NFPA 54), septic tank, pressure loss

▸ HVAC (8)
• Manual J heat load
• Duct sizing (ASHRAE equal friction)
• Refrigerant charge
• Air changes per hour (ACH)
• Tonnage, heat loss, SEER savings, CFM per ton

▸ CONSTRUCTION (26)
• Concrete volume (slabs, footings, columns) and bag count
• Board feet for lumber takeoffs
• Stud count for framing
• Drywall sheet count
• Roofing squares, roof pitch, rafter length
• Stair rise and run (IRC R311.7)
• Paint, tile, flooring, deck, fence, paver, and more

▸ WHY FieldDojo
• 100% offline — works in basements, attics, crawl spaces, no signal needed
• Imperial and metric, switch instantly
• History saved automatically — last 30 results free, unlimited with Pro
• Text share free; PDF reports with Pro
• No ads, no popups, no tracking inside calculations
• Clean interface designed for gloved hands and bright sunlight

▸ FIELDDOJO PRO (optional)
Cloud sync, PDF reports, unlimited history, unlimited projects. $4.99/month, $29.99/year, or $79.99 once. Every calculator stays free.

▸ FOR PROS, BY PROS
FieldDojo is not a homeowner toy. The formulas reference NEC, ACCA Manual J, ASHRAE, UPC/IPC, NFPA 54, and IRC. Each calculator shows the formula and the code table so you can verify, document, or teach an apprentice.

▸ NOT A SUBSTITUTE FOR CODE
FieldDojo is a calculation aid. Always verify against your local jurisdiction's adopted code, manufacturer specifications, and licensed engineering review where required. FieldDojo does not provide engineering, legal, or code-compliance advice.

Website: https://fielddojo.com
Support: [e-mail]
Privacy: https://fielddojo.com/privacy

What’s new

• FieldDojo Pro is now available on Android — cloud sync, branded PDF export, and unlimited history
• Export to CSV: project sheets, your projects list, and Quick Calc (free)
• PDFs show their work: inputs, code basis, and a signature block, with your company details in the header (Pro)
• New Company section in Settings
• Smoother, faster start after setup
• Fixes: email wrapping in Settings, project “not found” flash, CSV encoding in Excel