A circuit breaker size chart shows the correct breaker amperage, wire gauge, and protection type for every common household appliance and circuit. Using the right breaker size protects wiring from overheating and prevents fire hazards. This reference follows NEC (National Electrical Code) guidelines, including the 80% continuous load rule and GFCI/AFCI requirements.
NEC 80% Rule Calculator
Circuit Breaker Sizing Reference
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Protection Type Guide
Electrical Safety Tips
Never replace a breaker with a higher-amperage breaker to stop it tripping — investigate the cause first.
Wire gauge must match or exceed the breaker rating — never use undersized wire (e.g., 14 AWG on a 20A circuit).
All 240V circuits require a two-pole breaker occupying two panel slots.
Apply the NEC 80% rule: size the breaker so continuous load does not exceed 80% of breaker rating.
EV charger circuits must be sized at 125% of the charger's continuous current rating per NEC 625.22.
Hot tubs require a disconnect within sight of the tub and cannot be operated over 240V per NEC 680.
⚡ Always consult a licensed electrician for your specific installation. Local codes may exceed NEC minimums.
How to Use the Circuit Breaker Size Chart
This breaker size chart covers the most common household circuits and appliances, showing the correct breaker amperage, minimum wire gauge, voltage, and protection type requirements per NEC guidelines. Use it as a quick reference when planning new circuits, upgrading panels, or verifying existing wiring.
Step 1: Search for Your Appliance or Circuit
Type the appliance name into the search box — for example, dryer, EV charger, or kitchen. The table filters in real time. You can also filter by voltage (120V vs 240V) using the buttons at the top to narrow down the list quickly.
Step 2: Use the NEC 80% Rule Calculator
If you know the wattage of your load (from the appliance nameplate or spec sheet), enter it into the NEC 80% Rule Calculator along with the circuit voltage. The calculator divides watts by volts to get amperage, then divides by 0.8 (per the NEC continuous load rule), and rounds up to the next standard breaker size. This is the minimum code-compliant breaker size for that load running continuously (3+ hours).
Step 3: Check Wire Gauge Requirements
The Wire Gauge column shows the minimum AWG (American Wire Gauge) copper wire required for each circuit. Remember that AWG is counterintuitive — a lower number means a thicker, higher-capacity wire. For example, 10 AWG carries more current than 12 AWG. Always match or exceed the listed gauge; never use a thinner wire than specified for the breaker size. For aluminum wiring (common in older 240V circuits), consult an electrician — aluminum requires larger gauges and special connectors.
Step 4: Verify Protection Type Requirements
The Protection column indicates whether a circuit requires a standard breaker, GFCI protection, AFCI protection, or a dual GFCI/AFCI combination breaker. GFCI protection is mandatory in wet locations — bathrooms, garages, kitchens, and outdoors — to prevent electrocution. AFCI protection is required by NEC 2020 in most living areas to prevent arc-fault fires. Local codes may adopt earlier or stricter versions of the NEC — always verify with your local authority.
Understanding 120V vs 240V Circuits
Standard 120V circuits power most outlets, lighting, and small appliances. Large appliances — electric dryers, ranges, water heaters, air conditioners, EV chargers, and hot tubs — run on 240V and require a two-pole breaker that occupies two slots in the panel. The breaker amperage listed for 240V circuits refers to each leg; the two-pole breaker protects both simultaneously.
Important Disclaimer
This circuit breaker size chart is provided for reference and planning purposes only. Electrical panel work involves lethal voltages and must be performed by a licensed electrician. Local codes may have requirements that exceed or differ from NEC minimums. Always obtain the required permits and inspections for new electrical work.
FAQ
Is this breaker size chart free to use?
Yes, this circuit breaker sizing chart is completely free. It runs entirely in your browser — no signup, no account, and no data is sent to any server. Bookmark it for quick reference when planning electrical work.
Is my data private when using this tool?
Yes, all calculations happen locally in your browser. No data is transmitted to any server. The tool works entirely offline once the page is loaded.
What is the NEC 80% rule for circuit breakers?
The NEC (National Electrical Code) 80% rule states that a circuit breaker should not be loaded to more than 80% of its rated amperage for continuous loads (loads that run for 3 hours or more). For example, a 20A breaker can safely carry 16A continuously. This prevents overheating and nuisance trips.
How do I calculate what size breaker I need?
Divide the load wattage by the circuit voltage to get amperage (Amps = Watts ÷ Volts), then divide by 0.8 to apply the NEC 80% rule. Round up to the next standard breaker size (15, 20, 30, 40, 50, 60A). The NEC 80% calculator on this page does this automatically.
What is the difference between GFCI and AFCI breakers?
GFCI (Ground Fault Circuit Interrupter) protects against electrical shock by detecting current leaking to ground — required in wet areas like bathrooms, kitchens, garages, and outdoors. AFCI (Arc Fault Circuit Interrupter) protects against fire by detecting dangerous arc faults in wiring — required by NEC in bedrooms and most living areas in new construction.
Can I use a larger wire gauge than required?
Yes, using a larger (lower AWG number) wire than required is always acceptable and increases safety margins. However, the breaker size must still match the circuit's design load and the minimum wire gauge for that breaker. You should never use wire that is too small for the breaker size — undersized wire is a fire hazard.
Why do 240V appliances like dryers and ranges need two-pole breakers?
240V appliances require two 120V legs from the electrical panel (each on a different phase), combined to create 240V. A two-pole breaker occupies two slots in the panel and connects both legs. If one leg trips, the breaker cuts both legs simultaneously to prevent partial energization of the appliance.
Do I need an electrician to size and install circuit breakers?
Yes. While this chart provides reference information, all electrical panel work must be performed by a licensed electrician and inspected to code. Incorrect breaker sizing can cause fire hazards, equipment damage, and code violations. Always consult a licensed electrician for your specific installation.