An electrical panel load calculator adds up the amp draw of your home's appliances and compares it against your service panel capacity (100A, 150A, or 200A). Use it before adding a heat pump, EV charger, or other high-draw appliance to see if a panel upgrade is needed.
Panel Service Size
Appliances (check all that apply)
Panel Load Analysis
Select your appliances to see panel load analysis.
How to Calculate Electrical Panel Load
An electrical panel load calculation determines whether your home's service panel can safely handle all current and planned electrical loads. The NEC (National Electrical Code) requires that total continuous load not exceed 80% of panel ampacity. A 200A panel can safely carry 160A of continuous load.
Understanding 240V vs 120V Loads
Large appliances (HVAC, water heater, range, dryer, EV charger) use 240V circuits and are the biggest consumers. A 40A 240V circuit delivers up to 9,600 watts. General lighting and outlets use 120V circuits — multiple 15-20A circuits, but each circuit rarely runs at full load simultaneously. Our calculation uses a demand factor for 120V loads (typically 60-70% actual utilization).
NEC 80% Continuous Load Rule
Per NEC 230.42, continuous loads must not exceed 80% of the service rating. A 200A panel supports 160A continuous load. When calculating whether you can add an EV charger, add its amp draw to your current load. If the total exceeds 160A, you technically need a panel upgrade or a load management device.
Smart Load Management Alternative
If your panel load is too high for an EV charger, smart load management devices (like Emporia Smart Charger or ChargePoint's adaptive charging) can share circuits with existing loads. They reduce EV charging speed when other loads are high, avoiding panel upgrades. This can be a $300-$500 alternative to a $3,500-$5,000 panel upgrade.
When You Need a 200A Upgrade
Signs you likely need a 200A service upgrade: (1) you have a 100A panel and want to add any 240V appliance, (2) your breakers trip frequently, (3) lights dim when large appliances start, (4) you're adding both a heat pump and EV charger to an existing 150A panel. A 200A upgrade for electrification-enabling projects qualifies for up to $4,000 in HEEHRA rebates.
FAQ
Is this electrical panel load calculator free?
Yes, completely free with no signup required. Load estimates use NEC (National Electrical Code) simplified load calculation methodology. For a licensed permit-ready calculation, hire a licensed electrician.
Do I need a 200 amp panel upgrade for a heat pump?
Many homes can add a heat pump on existing 200A service. However, if you're already running electric resistance heating, electric range, electric dryer, and high-load HVAC, you may be near capacity. Adding a heat pump (30-40A), EV charger (40-50A), and heat pump water heater (30A) simultaneously can exceed 200A service. Check your current load first.
How many amps does an EV charger add to my panel?
A Level 2 EV charger typically requires a dedicated 40-60 amp breaker (32-48 amp continuous load under NEC 80% rule). A 48A EV charger needs a 60A dedicated breaker. On a 200A panel that's already using 150A for other loads, there's only 50A left — enough for one 40A charger but not two 60A chargers.
What is NEC 80% panel loading rule?
NEC 230.42 requires that continuous loads (running 3+ hours) be limited to 80% of circuit rating. Your panel service can be loaded to 80% continuously for safety and code compliance. A 200A service should not exceed 160A continuous load. Our calculator applies this rule automatically.
How much does a 200 amp panel upgrade cost?
A 200A service upgrade (from 100A or 150A) typically costs $2,500-$5,000 including the new panel, main breaker, and electrician labor. If the utility needs to upgrade service entrance wiring, add $500-$2,000. Federal IRA rebates of up to $4,000 are available for qualifying income levels to cover panel upgrades needed for electrification.
Is my data safe?
Yes. All calculations run in your browser. No data is transmitted or stored.