Wire Gauge Ampacity Calculator
Safe current rating for common copper wire gauges.
Enter your values
Choose one of: 14 AWG, 12 AWG, 10 AWG, 8 AWG, 6 AWG, 4 AWG, 2 AWG.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Rated ampacity (60°C copper)
- 20 A
- Recommended max continuous load (80%)
- 16 A
- Wire gauge
- 12 AWG
Quick answer
Ampacity depends on wire gauge, insulation type and installation conditions.
Lookup by AWG (60C copper, NEC Table 310.16 style)
At a glance
| What it does | Safe current rating for common copper wire gauges. |
|---|---|
| Category | Engineering |
| Inputs needed | Wire gauge (AWG) |
| Main output | Rated ampacity (60°C copper) |
| Formula | Lookup by AWG (60C copper, NEC Table 310.16 style) |
| Cost | Free — no sign-up, no download |
How to use the Wire Gauge Ampacity Calculator
- 1Choose the copper wire gauge you are working with.
- 2Read the standard ampacity rating for general-purpose 60C insulation.
- 3Apply the 80% continuous-load derating used in most electrical codes.
Inputs explained
- Wire gauge (AWG)
- Choose one of: 14 AWG, 12 AWG, 10 AWG, 8 AWG, 6 AWG, 4 AWG, 2 AWG.
Worked example
Using the values the calculator loads with:
Inputs
- Wire gauge (AWG)12 AWG
Results
- Rated ampacity (60°C copper)20 A
- Recommended max continuous load (80%)16 A
- Wire gauge12 AWG
Frequently asked questions
Why derate to 80%?
Continuous loads run for 3+ hours and codes require sizing at 80% of the breaker/wire rating to prevent overheating.
Does insulation type matter?
Yes, 75C and 90C rated insulation allow higher ampacities on the same gauge; check your local code table.
What do I need to enter into the Wire Gauge Ampacity Calculator?
Just 1 value: wire gauge (awg). Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Wire Gauge Ampacity Calculator work out the answer?
Ampacity depends on wire gauge, insulation type and installation conditions. It applies the formula Lookup by AWG (60C copper, NEC Table 310.16 style) and shows the working so you can check each step by hand.
Is the Wire Gauge Ampacity Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.