AWG Ampacity Calculator
Look up the diameter, cross-section, and resistance of an American Wire Gauge size and see a guideline current-carrying capacity. Calculates in your browser.
Typical ampacity
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Show the math
Voltage drop is the round-trip resistance times the current:
Vdrop = I × (Ω/1000 ft ÷ 1000) × 2 × length
Ampacity figures are typical hobby/chassis-wiring values, always follow your local electrical code for real installations. All math runs in your browser.
What this does
An AWG ampacity calculator looks up the diameter, cross-section, and resistance of an American Wire Gauge size and shows a guideline current-carrying capacity.
How to use it
- Select the AWG size.
- Read the diameter and cross-section.
- Check the resistance per length.
- See the guideline ampacity.
How it works
Each AWG step changes the diameter by a fixed ratio, so cross-section roughly doubles every three sizes. Ampacity depends on gauge, insulation, and installation, and these figures are general guidelines, not code-compliant.
Understanding your result
These ampacity figures are general guidelines, not code-compliant ratings: the safe current for a gauge depends heavily on insulation type, ambient temperature, and how the wire is bundled or routed. Use the resistance figure to check voltage drop on long runs, and always size real wiring to your local electrical code and the breaker protecting it, not to a rule of thumb.
Example
12 AWG copper is rated around 20 A in typical residential wiring.
Sources & methodology
Last updated .
Frequently asked questions
What is ampacity?
Ampacity is the maximum current a conductor can carry continuously before its temperature rating is exceeded. It depends on gauge, insulation, and installation.
Are these values code-compliant?
No — they are general guidelines. Always follow your local electrical code (e.g. NEC tables) and consult an electrician for real installations.
Is my data stored?
No. Everything is calculated locally in your browser.
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