20 calculators · 9 learning tools · advanced preview open

Electrical calculations
you can inspect.

Results expose formulas, substitutions, and known assurance limits. Advanced routes are free to evaluate while the correctness audit is active.

For Students — FreeAdvanced Preview — Free
20
CALCULATORS
9
LEARNING TOOLS
11
ADVANCED PREVIEW
ACTIVE
CORRECTNESS AUDIT
Specimen — Calc 01 · Ohm's LawSheet 1/1
Current I
10 A
Resistance R
1.2 Ω
Derivation
01V = I × R
02V = 10 × 1.2
Voltage — Result
12.0 V
CHECKS PASSED 3/3

Actual output format — every calculator produces an inspectable sheet like this.

Track A — LearnFREE

For Students

Step-by-step derivations
Every answer shows the formula and the substitution behind it
Check your reasoning
See the inputs, formula, substitution, and result together
No signup required
Open a calculator and start — free forever
Explore the free tools
Track B — DesignPREVIEW

For Professionals

Visible assurance boundaries
Verified extracts, screening paths, and refusals are distinguished
Explicit engineering inputs
Manufacturer and tariff values are requested instead of silently guessed
Inspectable output
Dense inputs, derivations, and warnings work on desktop and mobile
Review the advanced preview
Task Index

All 20 Calculators

9 Free 11 Advanced Preview
BASIC
01Ohm's Lawfree02Series / Parallel Resistorsfree03Voltage / Current Dividerfree
ELECTRONICS
04LED Resistorfree05Battery Lifefree
POWER SYSTEMS
06Three-Phase Powerfree07Transformer Sizingfree08Cable Sizingpreview09Power Factor Correctionpreview
MOTORS
10Motor Sizingpreview11Motor Starting Currentpreview
PRACTICAL
12Wire Gauge + Voltage Dropfree13Energy Costfree14Conduit Fillpreview15Breaker Sizingpreview
SOLAR PV
16Solar Panel Sizingpreview17Inverter Sizingpreview18Battery Bank Sizingpreview19String Configurationpreview20Solar ROIpreview
Access Levels

Choose Your Path

Level 1 — StudentFREE
  • 9 calculators — basics, electronics, practical
  • Full step-by-step derivations
  • Visible formulas and assurance boundaries
  • No signup required during the correctness audit
Start Learning
Level 2 — Advanced PreviewFREE DURING AUDIT
  • All 20 calculator routes, including the Solar PV suite
  • Verified extracts where available; screening/refusal elsewhere
  • No checkout, subscription, or paid entitlement
  • Not represented as permit-ready or final equipment selection
Review Access Status
Reference Standards
NEC 2023 (NFPA 70)Verified extracts in use: Tables 310.16 / 310.15(B)/(C) · 240.4 / 240.6(A) · 430.52 · Chapter 9 · 314.16 · 110.14(C)
—IEC 60364 — roadmap, not yet supportedNo IEC table cells are extracted or verified yet, so no result is calculated to IEC.
—วสท. 022001-22 (2564) — not yet supportedDocument identity verified only — no conductor, protection, raceway, or voltage-drop values are extracted yet.