WireGaugeCalc Free calculator · NEC cited · works offline
Dc Circuit Calculator
dc circuit calculator is simple with WireGaugeCalc, since it ties voltage, current, resistance, and power together through Ohm's law.
You enter any two known values and the calculator solves for the rest, so you can check a DC load fast.
The result gives you the figures needed to size conductors and confirm voltage drop.
Open the calculatorEnter any two values and read the rest.
Ohm’s law: V = I × R and P = V × I. Field aid only, verify against the current NEC and your local authority having jurisdiction.
How Ohm's law drives the DC math
Voltage equals current times resistance, so entering two values lets the app return the third without manual algebra.
Power equals voltage times current, which gives you the wattage of the load alongside the current it draws.
Because DC has no power factor, the math stays direct, so the numbers map cleanly to real loads.
What the calculator solves on a DC system
Enter what you know and read the rest:
- Current from voltage and resistance
- Resistance from voltage and current
- Power in watts from voltage and current
- Voltage drop across a run from current and wire resistance
- Load current to compare against conductor ampacity
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
Can I use this to check DC voltage drop?
Yes, enter the load current and the round-trip conductor resistance and the calculator returns the voltage lost on the run. Many DC systems target 3 percent or less, so confirm the limit for your application and verify against the current NEC and your local authority having jurisdiction.
Why is DC wire sizing often about voltage drop, not ampacity?
DC systems frequently run at low voltage like 12 or 24 volt, so a small voltage loss is a large percentage of the supply. The conductor that carries the current safely may still be too small to keep the drop acceptable.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.