WireGaugeCalc Free calculator · NEC cited · works offline
100 Ampplifier Wire Size Calculator
100 ampplifier wire size calculator is fast with WireGaugeCalc, since it reads the NEC 310.16 table and returns the conductor that carries 100 amps for your setup.
You enter the conductor material and the terminal temperature rating, and the tool returns the AWG or kcmil size that meets the 100 amp load.
That gives you a sized conductor right away so the feed is protected without overspending on copper.
Open the calculatorSmallest conductor whose ampacity meets the load, NEC Table 310.16. Field aid only, verify against the current NEC and your local authority having jurisdiction.
What carries 100 amps in copper and aluminum
Copper 3 AWG is rated 100 amps at the 75 degree column of NEC 310.16, so it is the common choice for a 100 amp feed on 75 degree terminals.
Aluminum needs 1 AWG to reach 100 amps at the 75 degree column, since aluminum carries less current per size than copper.
The wire size calculator checks the termination temperature first, so you do not size off a column your equipment is not rated for.
Sizing the conductor for a 100 amp load
The calculator weighs these inputs before it gives you a size:
- Conductor material, copper or aluminum
- Termination rating, usually 60 or 75 degrees C
- NEC 310.16 ampacity for the 100 amp target
- Continuous loads sized at 125 percent
- Long runs that may need an upsize for voltage drop
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 wire size do I need for a 100 amp circuit?
On 75 degree terminals, 3 AWG copper or 1 AWG aluminum carries 100 amps per NEC 310.16. The calculator confirms the size once you pick the material and temperature column.
Can I use 75 degree ampacity for sizing?
You can use the 75 degree column only when every termination and the equipment are rated for 75 degrees C. If anything is rated 60 degrees, size to the 60 degree column instead.
Should I upsize a long 100 amp run?
Yes, a long feed can drop more than 3 percent, so you may need a larger conductor to hold voltage. Verify the final size against the current NEC and your local authority having jurisdiction.
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.