// 17 Calculators · Free Tier

Electrical Calculators

Every calculation you run on a job. Use them free in your browser, or get the app and have all seventeen offline in a basement with no signal.

Each one shows the formula, the code section behind it, and the mistakes that come up in the field. Ampacity, voltage drop and fill are three separate checks, and passing one tells you nothing about the other two.

Voltage Drop
Drop across any run, single or three-phase.
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Box Fill
Cubic inches required under 314.16.
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Conduit Fill
How many conductors fit in a raceway.
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Wire Ampacity
310.16 with real derating applied.
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Breaker Sizing
Branch, feeder and continuous-load overcurrent.
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Load Calculation
Dwelling service sizing, Article 220.
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Conduit Bending
Offsets, saddles, kicks and stubs.
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3-Phase Power
kW, kVA, amps and power factor.
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Transformer
kVA to primary and secondary current.
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Ohm's Law
Volts, amps, ohms and watts.
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Grounding (GEC/EGC)
250.66 and 250.122 sizing.
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Motor Data (FLC/LRA)
Full-load current and circuit sizing.
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Conduit Sizing & OD
Outside diameters and knockout sizes.
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Support Spacing
Raceway and cable support intervals.
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Wire Torque Specs
Terminal torque under 110.14(D).
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Bolt Torque Specs
Structural and equipment fasteners.
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Cat 6 Wiring
T568A and T568B pinouts.
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EVERY CALCULATOR, FREE

No card, no trial timer. The free tier includes all 17 calculators and the full reference library.

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Frequently asked questions

Are the calculators free?
Yes. Every calculator and the full reference library are on the free tier, with no card required. The paid tiers buy more AI code assistant scans per day, not more calculators.
Do the calculators work offline?
Yes. Basements, mechanical rooms and rural service calls all kill your signal, so the calculators and reference tables work without a connection.
Do they use fractional inches?
Yes. Bending and conduit inputs take sixteenths, because that is what a tape measure reads. Decimal-only input is the fastest way to spot a calculator built by someone who has never held a bender.
Can I use these instead of the code book?
No. These are calculation and navigation tools. When there is money or a failed inspection on the line, the adopted code text and your AHJ are the authorities.
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// DisclaimerThe National Electrical Code® (NEC®) and NFPA 70® are registered trademarks and copyrighted publications of the National Fire Protection Association (NFPA). This article is an independent educational resource and is not affiliated with, endorsed by, or sponsored by the NFPA. All code references in this article are paraphrased for educational purposes only and do not reproduce the official text of any NEC edition. This content is not a substitute for the official NFPA 70 publication. Electricians, contractors, and students are encouraged to purchase the official National Electrical Code from the NFPA at nfpa.org for complete and authoritative code text. Always verify requirements with the code edition adopted by your jurisdiction and your Authority Having Jurisdiction (AHJ).