The complete toolkit
Electrical Calculators
Eleven free, NEC-2026-grounded calculators for electricians and homeowners. Every tool shows its formula and cites the code — instant answers, no sign-up.
V-DROP · NEC 3%
2.6%
120 V · 20 A · 100 ft on 8 AWG
One console. Eleven calculators. Watch it work.
NEC 2026-grounded
every formula cited
Formulas shown
no black boxes
Works anywhere
fast on mobile
Free, no login
no ads, no wall
Artie has taught physics and electrical theory for over a decade and consulted on real-world electrical design — so every tool here is grounded in both the theory and the field.
University physics lecturer·Consulted on commercial electrical systems·Last reviewed Jul 2026
The index
Eleven tools, four workflows
Every calculator runs on the same NEC-2026 engine and shows its math. Pick a workflow and open the one you need.
Wire & Circuit Sizing
Size conductors and protect them
Conduit & Raceway
Fit conductors in the pipe
Power & Current Conversions
Move between watts, amps, volts & PF
Loads & Backup Power
Size the service, backup & solar
Why these tools
Built to a higher accuracy bar
Plenty of sites will give you a number. Ours show their work and cite the code — because in electrical work a wrong number isn't a bug, it's a safety failure.
NEC 2026-grounded
Every tool follows the 2026 National Electrical Code and names the exact article behind each result.
Formulas in the open
No black boxes. Each calculator shows the formula it runs, so you can follow — and check — the math.
Verified numbers
Every worked example is checked in code before it ships. We treat a wrong result as a safety issue.
Free & unblocked
No sign-up, no ads, no paywall — and fast on the phone you're holding on the job.
The basics
Electrical calculators, explained
An electrical calculator turns a code rule or a formula into an instant answer. Instead of flipping through NEC tables to find a wire size, a voltage-drop percentage, or a breaker rating, you enter your numbers and read the result — with the formula shown, so you can trust it.
Electricians use them for fast field checks; engineers and estimators use them to spec jobs; and homeowners use them to plan a panel upgrade, a generator, or a solar array before calling a pro. The tools here flex for all three — plain-language where it helps, technical where it counts.
Because these numbers guide real installations, accuracy isn't optional. Every calculator on this page is grounded in the 2026 National Electrical Code, cites the article behind its result, and carries a plain disclaimer: results are for planning, and your local code and AHJ have the final say.
Are these electrical calculators free?
Yes — completely free. No sign-up, no paywall, no ads. Use any calculator as often as you like, on any device.
Which NEC edition do they use?
All tools follow the 2026 National Electrical Code and cite the specific article behind each result. Where a 2026-edition change is coming, we note it on the relevant page.
Are they for electricians or homeowners?
Both. They give electricians and engineers fast, code-accurate answers, and walk homeowners through the same math in plain language — so you can plan a panel, generator, or solar project before calling a pro.
Are the results accurate enough for a permit or inspection?
They follow NEC formulas exactly and are built for planning and estimating — but a permit or inspection needs a licensed electrician and your local AHJ's sign-off. Use these to get the numbers right, then confirm the install.
Do they work on mobile?
Yes. Every tool is mobile-first and loads fast, so it works on the phone you're holding on the job — no app to install.
Do I need to create an account?
No. There's no account, no email, and nothing to unlock. Open a calculator and use it.
Do they cover single-phase and three-phase?
Yes — the sizing and conversion tools handle DC, single-phase, and three-phase, and let you set your actual voltage (120 V, 240 V, 480 V, and more).
How do you make sure the numbers are right?
Every formula is validated against its NEC reference, and every worked example is checked in code before it ships. We treat a wrong number as a safety failure — and each tool shows its formula so you can verify it yourself.
Keep going
Start with the most popular
You’ve got the amps — now put them to work. These pick up from there: convert watts, size the wire for the load, and see the V · I · R · P relationship behind it.
How we keep this accurate
Every tool is grounded in the National Electrical Code (NEC 2026) — or NREL data for solar — shows its formula, and cites its source. Results are for planning and estimating. Code adoption, local amendments, and field conditions vary — verify with your AHJ and a licensed electrician before installation.