An electrical panel load calculator works out how much electrical demand your home or small business actually draws, in amps and watts, against the rating of your panel and service. It applies the demand factors of the National Electrical Code (NEC) to your lights, outlets, appliances, and HVAC, then returns the number every power decision hangs on.
What is my current panel load in amps? The calculator returns the real draw of your home against your panel rating.
How much spare capacity do I have left? The calculator shows your remaining amps against the 80% continuous limit.
The calculator gives a clear verdict — overloaded, tight, or OK — so you know before you add a circuit or an EV charger.
The difference between connected load and demand load is the whole game. Connected load is every watt of everything installed. Demand load is what the house actually draws at its peak, after demand factors, because nothing runs at full capacity at the same time. A 200 amp panel can legally hold 400 amps of breakers, and a home at 80 amps of real demand is nowhere near overloaded. Code-based demand factors turn the first number into the second, and that's the figure that sizes your service, your panel, and your backup generator.
What is my current panel load in amps? The calculator returns your exact draw in amps and watts against your panel rating.
How much spare capacity do I have left? The calculator shows your remaining amps and utilization percentage.
Is my panel overloaded? The calculator gives a clear verdict based on the 80% continuous load limit.
Can I add a Level 2 EV charger or a new circuit? The calculator shows if your panel has room for the extra load.
Enter your panel size, square footage, and appliances. The calculator applies NEC 220.82 demand factors and returns your load in amps, spare capacity, overload verdict, and EV charger fit.
Fill in your panel size and home characteristics. Equipment defaults are pre-loaded for a typical residence.
Edit values to match your home. Lighting and laundry are auto-calculated.
The chart below is a planning reference for the common residential and light-commercial service sizes.
| Panel / Service | Theoretical Max | 80% Continuous Limit | Typical Home Usage |
|---|---|---|---|
| 100 A | 24,000 W | 80 A (19,200 W) | Older and smaller homes, often tight for all-electric |
| 150 A | 36,000 W | 120 A (28,800 W) | Mid-size homes with gas heat |
| 200 A | 48,000 W | 160 A (38,400 W) | Most homes use 80 to 90 A at peak |
| 400 A | 96,000 W | 320 A (76,800 W) | Large estates, shops, light commercial |
2,500 sq ft all-electric home with a 200 A panel, 5,000 VA heat pump, electric range and dryer.
Lighting: 2,500 × 3 = 7,500 VA. Laundry: 1,500 VA. Range + dryer: 6,000 VA.
Demand factor: first 10,000 VA at 100%, remainder at 40% = 10,000 + (5,000 × 0.4) = 12,000 VA.
HVAC: 5,000 VA. Total: 12,000 + 5,000 ≈ 17,000 VA ≈ 71 A at 240 V.
EV charger test: Add Level 2 (40 A, 9.6 kW, 125% continuous = 50 A). Home lands at 121 A, under the 160 A line. Fits — no panel upgrade needed.
That's the honest answer the calculator gives: a verdict on your panel today, and a second verdict the moment you add the next appliance.
To calculate electrical panel load, total your lighting at 3 VA per square foot, add 1,500 VA for laundry and each appliance circuit, apply the demand factor, add the larger of your heating or cooling load, then divide the total VA by 240 volts to get amps. Compare the result against 80% of your panel rating.
Lighting at 3 VA per square foot, 1,500 VA for the laundry circuit, and the nameplate load of each major appliance — range, dryer, dishwasher, water heater, and any other fixed equipment.
The first 10,000 VA counts at 100%, and everything above it at 40%. This accounts for the fact that not all loads run at full capacity simultaneously in a typical home.
Count only the larger of the two — heating or cooling — because they do not run together. Include the air conditioner compressor, heat pump, or electric furnace nameplate rating.
Divide the total volt-amps by your system voltage — 240 V for a typical home — to get the load in amps. This is the actual current draw your panel must support under normal conditions.
A continuous load may use only 80% of the panel rating. A 200 amp panel's practical ceiling is 160 amps. If your calculated load exceeds that, it's time to upgrade or redistribute.
Lighting: 2,000 × 3 = 6,000 VA. Laundry: 1,500 VA. Appliances (range, dryer, dishwasher): 14,200 VA. Subtotal: 21,700 VA. Demand: first 10,000 VA at 100% = 10,000 VA; remaining 11,700 VA at 40% = 4,680 VA. Subtotal: 14,680 VA. HVAC (5,000 VA, larger than heating): total 19,680 VA. 19,680 ÷ 240 = 82 A. A 200 A panel at 80% = 160 A capacity, so this panel has 78 A of spare capacity.
Most overloaded panels announce themselves before they fail. Our engineers and the electricians we work with see the same patterns — here are the six most common indicators that your panel may be near its limit.
The main breaker, or a branch breaker, kicks off when two big loads run together. If this happens regularly with no clear cause, the panel is likely being pushed beyond its capacity.
Lights that flicker or dim when the AC, the sump pump, or a space heater kicks on point to voltage sag under load — a classic sign of an overloaded or undersized service.
Heat is the overload's calling card. A warm panel or warm breaker handles indicate excessive current flow, which also damages the breakers over time and creates a fire risk.
Frequent tripping in the kitchen or laundry, where loads stack up — toaster, microwave, dishwasher, dryer — suggests the branch circuit is overloaded and the panel may be nearing its limit.
The panel is full of breakers and you need one more circuit. A fully populated panel often means the service was sized for yesterday's loads, with no allowance for future additions.
When the service can't hold the voltage under load, appliances run sluggish — motors slow down, compressors strain, and performance drops. This is a strong indicator of an overloaded panel.
Our engineers see these five errors more than any others on residential and small commercial jobs. Avoiding them saves money, prevents nuisance trips, and keeps your electrical system safe.
A 200 amp panel can hold 400 amps of breakers and be code-legal. Breakers protect wires; load diversity decides the real demand. Adding breaker ratings tells you nothing about actual load.
Counting every connected watt with no diversity oversizes the service, the panel, and any generator you buy. The NEC demand factor exists because loads don't all run at once — use it.
Treating a 200 amp panel as 200 amps of usable load invites nuisance trips and an overheated panel. Continuous loads must not exceed 80% of the breaker or panel rating — 160 amps for a 200 A panel.
EV chargers, well pumps, and sump pumps run for hours at a stretch. These continuous loads count at 125% of their nameplate rating when sizing the circuit and the panel.
For an existing home, a utility smart-meter peak — run through NEC 220.87 — beats any estimate. A clamp meter on the service conductors gives you live amps, and the data is free from your utility.
If you see the warning signs, the real check is to measure, not guess. A clamp meter on the service conductors gives you the live amps, and your utility's smart-meter data — downloadable as a Green Button file — gives you the actual 12-month peak. The calculator runs the NEC 220.87 real-usage method on that number: your peak demand times 125%, plus any new load times 125%, must stay under the panel rating.
Our engineers will review your panel load calculation, confirm your spare capacity, and deliver a factory-direct price — no obligation, no hidden fees. Every quote includes the generator, automatic transfer switch, and soundproofed enclosure for a complete home backup solution.
A: Total your lighting at 3 VA per square foot, add 1,500 VA for laundry and each appliance circuit, apply the demand factor, add the larger of heating or cooling, then divide by 240 V to get amps. Compare the result against 80% of your panel rating.
A: Most homes run 80 to 90 amps at peak, and a 200 amp panel carries them comfortably. The calculator returns your exact number from your square footage and appliances.
A: If breakers trip, lights flicker, or the panel feels warm under normal loads, get it checked. Run the calculation and compare against the 80% headroom line, then have a licensed electrician confirm.
A: A 200 amp panel carries up to 200 amps briefly, but the continuous planning limit is 80%, or 160 amps. A home at 71 amps has roughly 89 amps of spare capacity.
A: Not always. A 200 amp home with typical loads fits a Level 2 charger at around 121 amps, inside the 160 amp headroom. A 100 amp panel usually needs an upgrade, an EVEMS load controller, or a dedicated circuit plan.
A: No. Breaker sizes protect wiring, and their total means almost nothing about your real load. Use the demand-factor method or a real-usage measurement instead.
A: The panel size doesn’t set the generator size. Essentials-only backup runs 7.5 to 10 kW, a typical 200 amp home runs 17 to 20 kW, and larger homes run 20 to 30+ kW with load management.
A: Yes. We build standby and prime diesel generators from 8 kVA to 4,000 kVA with automatic transfer switches, soundproofed enclosures, and factory-direct quotes, and we size them on your real panel load.
