Free tool · Panel capacity
Will my panel handle an EV charger?
Check whether your electrical service has room for a Level 2 charger. Upload your smart meter data for the most accurate answer, or estimate from your home and appliances. See in seconds whether a Level 2 charger fits.
Step 1 · Start with a home like yours
Check your panel with your real usage
Where do I find this?
Open your electrical panel. The biggest breaker, usually at the top and set apart from the rest, has a number on its handle like 100, 150 or 200. That’s your service size in amps. No main breaker? Use the panel’s rating from the label inside the door (for example “200A”) for now. Not sure? Pick “Not sure” and we’ll assume 150A to be safe.
What does this mean?
The code counts 3 watts per square foot for lights and outlets, so bigger homes start with a bigger base load. Your appraisal or listing has the number.
How big is my AC?
Look at the label on the outdoor unit. The model number has a two-digit number like 24, 30, 36, 48 or 60 in it. Divide by 12 for tons: 36 means 3 tons, 48 means 4 tons. Not sure? Most Texas homes need about 1 ton per 500 to 600 sq ft.
Which one do I have?
If your thermostat says “heat pump,” “aux heat” or “emergency heat,” you have a heat pump with backup heat strips. If the heat is electric but there’s no heat pump, it’s an electric furnace. The kW is on the label of the indoor unit, often in the attic or a closet. Add up all units. Not sure? Pick 10 kW.
About your panel (recommended)
What does this mean?
Some older brands, like Federal Pacific and Zinsco, have known safety problems. We won’t add a charger to those and recommend replacing the panel first.
What does this mean?
A 60-amp breaker for a charger takes two side-by-side spaces. A full panel can often be fixed with slim breakers or a small subpanel; we check from your photos.
What does this mean?
Solar and batteries supply some of your power before it reaches the meter, so meter data understates your real load. With solar or a battery we use the home estimate instead.
Your smart meter records your home’s power use every 15 minutes. The code lets us size a charger from your real busiest moment in the past year instead of an estimate. It’s the most accurate answer, and it often shows more room.
What does this mean?
Your utility owns the meter and keeps your 15-minute readings. Where you download them depends on the utility, so the steps below change when you pick yours.
What does this mean?
Your highest 15-minute reading, usually on a hot summer afternoon with the AC running, is the one number the code uses to size a charger from real data. Take the tallest bar from the last 12 months.
Checking
Your result
Charger speed
Ways to make it fit
Show the math
How the check works
The electrical code gives two ways to check an existing home. The calculator does both. Your home’s busiest moment is what matters, not your monthly bill.
Load calculation
Add up your home: 3 watts per square foot for lights and outlets, the kitchen and laundry circuits, your AC or heat (whichever is bigger), and every big appliance at its nameplate rating. The first 8 kW counts in full and the rest at 40%, because not everything runs at once. Then the charger goes on top at 125%.
Your real usage
Or skip the math and use a year of smart meter data. Your highest 15-minute reading counts at 125% as the safety buffer, then the charger is added at its rating.
Your service
Either way, if the total stays under your main service size, the charger fits as is. Real usage data often shows more room than the calculation does.
If it doesn’t fit
Panel capacity questions
How do you calculate whether my panel can take a charger?
The electrical code lets us use a year of your real usage. We take your highest 15-minute demand from the past 12 months, count it at 125% as a safety buffer, add the charger at its rating, and check that the total stays under your service size. Without usage data, we use the standard calculation for an existing home based on its size and appliances.
Where do I find my 15-minute usage data?
If your utility (the company that owns the poles and wires) is Oncor, CenterPoint, AEP Texas or TNMP, your 15-minute data is on Smart Meter Texas. Austin Energy, CPS Energy and most co-ops show it on their own customer portals. Send us the file or a screenshot of the highest reading and we’ll do the math.
What if the calculator says it doesn’t fit?
You still have options. Load management lets a full-speed charger share your service by slowing down when the house is busy. A smaller charger may fit as is. If the panel is old or the service is small, an upgrade or a SPAN smart panel may be the better long-term answer.
Is load management safe?
Yes. A load manager measures your whole home’s power use and turns the charger down before the service is overloaded. Our first choice is a Tesla Universal Wall Connector with a Tesla energy meter; Emporia has its own option too.
Why does the charger count at 125%?
EV chargers run at full power for hours, so the code treats them as a continuous load and sizes the circuit at 125% of the charger’s rating. That’s why a 48-amp charger goes on a 60-amp circuit.
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Ready for a real number?
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Send three photos of your panel and where you park. If your panel looks tight, we’ll ask for your usage data and run the real numbers for free.
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