Build Calculator Apps for One Licensed Trade

1. 1

   Respect the code copyright from day one

   The National Electrical Code belongs to the NFPA, and welding procedure standards belong to AWS; you cannot republish their tables without a license. Build calculators that implement the math and cite the governing section numbers, license content where you truly need it, and have someone credentialed in the trade verify every formula. Getting this wrong is both a legal and a safety problem.

2. 2

   Pick the five calculations that run daily

   For electricians that is voltage drop, conduit fill, box fill, ampacity with derating, and motor calculations; for welders it is parameter selection by process, position, and material. Interview working tradespeople and rank by frequency, not by what is easy to build.

3. 3

   Design for gloves, glare, and no signal

   Everything works offline, buttons are huge, results show the work so a suspicious old-timer can check it, and each result can be saved to a job record. Field conditions are the spec; a beautiful app that needs two hands and LTE loses to a laminated card.

4. 4

   Keep pace with code cycles

   Codes revise on multi-year cycles and states adopt different editions, so let users pick their jurisdiction's edition. The update treadmill is your moat: abandoned competitors die exactly here, and your subscription price is justified by staying current.

5. 5

   Sell where the trade already talks

   Trade subreddits, licensing exam prep groups, supply counter flyers, and instructors at community colleges reach the whole market. Apprentices studying for exams are a natural entry point who carry the app into their careers.

6. 6

   Expand as a family of trades

   Once the electrician toolkit earns trust, the same playbook builds the plumber, HVAC, and welder versions as separate focused apps under one account. Separate apps rank better in app-store search than one bloated bundle.

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