Electrical Load Calculator – Size Your Panel Without the Guesswork
Use our free electrical load calculator to size your service panel. Includes NEC loads, EV chargers, and heat pumps. No email required. Try it now.
✅ Free · No signup · No email required📊 Data from public industry sources🕐 Prices updated June 2026🔒 We never see your data🧑💻 Built by AmpFlow · About us
Why You Need an Electrical Load Calculator
📊 Data sourced from publicly available industry standards. See our methodology page for formulas, sources, and limitations.
Residential Load Calculator – Technical Manual
NEC-compliant (Article 220) load estimation for single-family dwellings.
1. Scope & Limitations
- Purpose: Provide preliminary NEC-based load calculations (VA) and recommended service size.
- Applicable Standard: National Electrical Code (NEC) 2023, Article 220 – Dwelling
NEC Standard Load Values Used in This Calculator
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Old Load Calculator vs. AmpFlow: What's Different?
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How to Use Your Results
Once you hit calculate, you'll see three numbers: total load in VA (or kW), recommended service size in amps, and estimated monthly cost. Here's what to do with them. If your calculated load is under 15,000 VA, a 100-amp panel might work—but check your local code. Between 15,000 and 30,000 VA? You're likely looking at 200 amps. Over 40,000 VA? That's a 400-amp service, usually for large homes with electric heating and multiple EVs. I've found that most modern homes with a heat pump and one EV need at least 200 amps. And if you're planning a renovation, always oversize by 25%. You'll thank yourself later.
Frequently Asked Questions
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Ready to Size Your Panel?
Don't guess. Use the calculator above, then talk to a licensed electrician. They'll verify your numbers and handle the permit. For most homes, a 200-amp panel is the sweet spot—it handles modern loads and gives you room to grow. Based on real data from the NEC and DOE, this tool gives you a solid starting point. Honestly, it's saved me hours of manual math.
AmpFlow Pick•Our Recommendation
AmpFlow 200-Amp Load Center Panel
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Frequently Asked Questions
- What is an electrical load calculation?
- It's the process of adding up all the electrical loads in a home to determine the minimum service size (in amps) needed for the panel. The NEC outlines the standard method.
- Do I need a permit to upgrade my panel?
- Yes, in most areas. A licensed electrician must pull a permit and do the work. The load calculation helps justify the upgrade to the inspector.
- Can I use this calculator for a commercial building?
- No—this is designed for single-family homes per NEC residential rules. Commercial buildings use different demand factors and load categories.
- How accurate is the monthly cost estimate?
- It's based on your total load and the average electricity rate you enter. The default rate is $0.145/kWh from EIA data. Actual costs vary by region and usage patterns.
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