WireGaugeCalc Free calculator · NEC cited · works offline
Total Demand Calculor
Total demand calculor is fast with WireGaugeCalc, since you enter each load in volt-amperes and the tool sums them for you.
It applies the standard NEC demand factors to general lighting, appliances, and other loads, so the result reflects calculated demand instead of a raw connected total.
You get a single demand figure in amps, so you can size the service or feeder without working the math by hand.
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 the Demand Load Calculation Works
Connected load is the sum of every load on the system, but the NEC lets you reduce it with demand factors since not every load runs at once.
The calculator converts your total VA to amps using the system voltage, so you see the demand current the service must carry.
Clear inputs mean you can adjust a load and watch the demand update right away.
What the Service Demand Tool Covers
Enter your loads and let the tool handle the demand math:
- General lighting load by area at 3 VA per square foot
- Small-appliance and laundry branch circuits at 1500 VA each
- Demand factors applied to the first 3000 VA and the remainder
- Fixed appliances totaled and reduced where the NEC allows
- Largest motor load added back at 125 percent
- Final demand shown in both VA and amps
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
What is the difference between connected load and demand load?
Connected load is the total of all loads added together. Demand load is that total after NEC demand factors are applied, since the code assumes loads do not all peak at the same time.
Does the calculator use the standard or optional method?
It follows the standard demand-factor approach for general and appliance loads. Confirm your numbers against the current NEC and your local authority having jurisdiction before you finalize a service size.
How do I turn demand VA into a service amp rating?
Divide the demand VA by the system voltage to get amps. For a 120/240 volt single-phase dwelling, divide by 240.
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.