Electrical Load Calculator:
does your panel have room?
Before you buy the EV, the heat pump, or the hot tub, find out what your service can actually carry. This runs the same NEC Article 220 math a Nevada electrician runs — in about two minutes, with the nameplate numbers you already have.
Residential load calculator
2023 NEC Article 220 standard-dwelling method — planning estimate only
Your home
NEC 220.41 · 210.11(C)Major appliances
NEC 220.55 · 220.54Use the nameplate on each appliance. Label shows amps instead of watts? Multiply: volts × amps = watts. Enter 0 for anything gas — gas appliances draw no electrical load here.
Fixed appliances
NEC 220.53Four or more and the code lets them share — a 75% demand factor applies automatically. Common ratings shown as placeholders; your nameplate wins.
Largest motor
NEC 220.50 · 430.24Planning to electrify?
NEC 220.57Add a future Level 2 EV charger to see tomorrow's load next to today's. The code counts EV charging at its full continuous rate (minimum 7,200 VA).
Your results
118 amps
28,300 VA (28.3 kW) calculated load
Amber = today's calculated load · navy marker = your 200A service
Your calculated load sits comfortably inside a 200-amp service. Adding new circuits or appliances still deserves a load check, but the math looks friendly.
- Recommended service
- 125 A
- Whole-house generator
- ~24 kW
Generator size is a starting point at 80% of the calculated load — real sizing must also handle motor-starting inrush. Minimum dwelling service is 100 A (NEC 230.79(C)).
See the NEC demand math →
- General lighting & receptacles10,500 VA before the NEC 220.45 demand split5,625 VA
- Electric range / ovenNEC 220.55 demand8,000 VA
- Electric dryerNEC 220.54 — 5,000 VA minimum5,000 VA
- Heating or cooling (larger of the two)They never run at the same time3,600 VA
- Fixed appliances (4 entered)8,100 VA × 75% — NEC 220.53 demand factor at 4+6,075 VA
- Largest-motor adder25% of the largest motor — NEC 220.500 VA
Planning estimate only, using the NEC 2023 standard dwelling calculation — not a substitute for a design by a licensed electrician. Final service and panel sizing must be verified on site and comply with NV Energy service requirements and the adopting jurisdiction (Reno, Sparks, Washoe County, or Carson City). Electrical service work requires a permit and inspection.
What this calculator is actually telling you
It converts your home into a single number — the minimum service size in amps that the National Electrical Code says your house needs. Everything else on the page is a consequence of that number: whether your existing panel has headroom, how big a standby generator would have to be, and whether the upgrade a salesperson quoted you is justified.
The method here is NEC Article 220's standard dwelling calculation. It starts from 3 VA per square foot of living space, adds the required kitchen and laundry circuits, then applies the demand factors the code allows — because no house ever runs everything at once. That is why a home with 60,000 watts of nameplate appliances does not need a 250-amp service.
When the number matters most
Before an EV charger
NEC 220.57 counts Level 2 charging at its full continuous rate — a minimum of 7,200 VA and often 11,500. It is the single largest load most homes ever add, and it is where 100-amp services run out of room.
Before going all-electric
Swapping a gas furnace or water heater for a heat pump moves load from the gas meter to your panel. Two swaps can consume the headroom a 200-amp service had.
Before sizing a generator
Generator dealers quote from square footage. The honest starting point is 80% of your calculated load — and then a real conversation about motor-starting inrush.
Before buying a battery
A battery is rated in continuous kW and usable kWh. The calculated load tells you which circuits it can realistically carry, and for how long.
Where estimates go wrong
- Confusing breaker space with capacity. A full panel and an overloaded panel are different problems with different prices. Only one of them needs a service upgrade.
- Using connected load instead of demand. Adding up every nameplate without the code's demand factors overstates the requirement badly, and it is how homeowners get sold 400-amp services they will never use.
- Ignoring the utility side. Your calculation can be perfect and still fail, because the service drop, meter base, and NV Energy's transformer all have to support the new size.
- Forgetting what is coming. Sizing exactly to today's load means paying twice. Use the EV planning step above to see tomorrow's number now.
Questions homeowners ask
What is an electrical load calculation?
It is the NEC Article 220 arithmetic that converts your home's square footage and appliance nameplates into the minimum service size in amps. It is what tells you whether a 100-amp panel can legally take an EV charger, and it is required on the permit for a service upgrade in Reno, Sparks, and Washoe County.
Can I use this calculator for my permit?
No. This is a planning estimate that uses the standard dwelling method. The calculation submitted with a permit has to be prepared and signed by a licensed electrical contractor, verified against your actual panel and NV Energy's service requirements. Use this to decide whether it is worth a call; we do the binding version at no charge.
My panel is full but the calculation says I have headroom. Now what?
Those are two different problems. Physical breaker space is solved by a sub-panel or a tandem-breaker rework. Electrical capacity is what this calculator measures. If you have capacity but no space, you do not need a service upgrade — and you should not be sold one.
The result says I am over my service rating. Do I need a service upgrade?
Not necessarily. A smart panel such as SPAN manages flexible loads so an EV charger and a heat pump never peak together, which frequently keeps a 200-amp service viable and costs less than a full upgrade. A genuine upgrade is the answer when the panel is also obsolete or the calculation is far over. We will show you both numbers.
Why does the calculator ask about heating and cooling separately?
Because NEC 220.60 lets you count only the larger of the two — a furnace and an air conditioner never run at the same time. In Northern Nevada, where summer cooling and winter heating loads are both real, which one dominates depends on whether your heat is gas or electric.
Get the binding calculation — free
A licensed Aspen electrician runs the formal NEC 220 calculation against your actual panel, meter, and service drop, then tells you plainly whether you need an upgrade, a smart panel, or nothing at all. NV License #0094927. $0 diagnostic fee.
Book Your Free Load Assessment