More loads and settingsCircuits, heat type, kitchen, hot tub, pool, motor, EV rule
Picking an appliance fills in typical running watts. Type the figure from the label if you have it.
See full breakdown
To calculate a home's electrical load, follow NEC Article 220: count 3 VA per square foot of living area, add 1,500 VA for each of the two small appliance circuits and 1,500 VA for laundry, then add the nameplate rating of fixed appliances such as the range, dryer, water heater and EV charger. Demand factors trim the total, so the optional method keeps the first 10,000 VA at 100% and counts the rest at 40%, and only the larger of heating or cooling goes in. Divide by 240 volts for amps and compare that with the rating on the main breaker.
How to calculate the electrical load of a house
The code gives two ways to run the numbers. This electrical load calculator does both: the optional method most electricians reach for first, and the longer standard method that works for any dwelling.
| Optional method existing or new home, service of 100 A or more | Standard method any dwelling | |
|---|---|---|
| General load | Floor area × 3 VA, plus 1,500 VA per kitchen and laundry circuit | Same figure, first 3,000 VA at 100% and the rest at 35% |
| Appliances | Nameplate of every fixed appliance, range and dryer included | Four or more fixed appliances at 75%, range and dryer by their own rules |
| Demand factor | First 8,000 VA (existing) or 10,000 VA (new) at 100%, the rest at 40% | Built into each line, plus 25% of the largest motor |
| Heating, cooling | Larger of the two, electric heat at 65% or 40% in a new home | Larger of the two at 100% |
| Service amps | (Demand load + heating or cooling) ÷ 240 V | Sum of every line ÷ 240 V |
Worked example: a 2,000 sq ft existing home adding a 48 A EV charger, optional method
The 34,820 VA is everything above the first block: floor area, circuits, range, dryer, water heater, kitchen appliances and the 11,520 VA charger. On a 100 A panel that is 8 A over, so the minimum becomes 125 A.
When to use this electricity load calculator
Run it before anything big gets wired in, and any time someone asks whether the panel is big enough.
- Adding an EV charger, heat pump or hot tub: each of these is a large load that runs for hours. Put it into the electrical load calculator with everything already in the house and you see whether the existing service still has room, or whether the charger tips it over.
- Planning a new service: new builds and major remodels start with this number.
- Sizing the main breaker, panel and wire: the calculated amps set the minimum service rating. Conductor size then follows from that rating and the local code, so treat the result as the starting point for the electrician, not the wire order.
- Generator or battery backup: list the circuits you want during an outage and size the unit from that load.
- Going all electric: swapping a gas range, dryer or furnace for electric adds thousands of VA, and the calculator shows how much.
- Energy budgeting: the Daily energy use tab turns appliance watts and hours into kWh per day.
- Quoting a panel upgrade: electricians can run the existing home method on the first visit and print a one page sheet that shows the homeowner why 100 A will not carry what they plan to add.
What does the NEC count in a residential load calculation?
These are the figures behind every line of the calculator. The 2026 edition of the NEC moves the same rules from Article 220 to Article 120, so inspectors may quote either number.
| Load | How it is counted | Figure |
|---|---|---|
| Lighting and receptacles | Outside dimensions, leaving out open porches, garages and unfinished areas. | 3 VA per sq ft |
| Kitchen and laundry circuits | Two or more kitchen circuits, one for laundry. | 1,500 VA each |
| Electric range | Standard method: one range up to 12 kW counts as 8 kW, plus 5% per kW above. | 8,000 VA up to 12 kW |
| Clothes dryer | 5,000 VA or the nameplate, whichever is larger. | 5,000 VA minimum |
| Fixed appliances | Water heater, dishwasher, disposal, microwave. | 75% when four or more |
| EV charger | 7,200 W or the nameplate, whichever is larger. | 7,200 VA minimum |
| Heating and cooling | They do not run together. | Only the larger counts |
| Electric heat, new home | Heat pump without strips in full, central heat or under four room heaters at 65%, four or more at 40%. | 100%, 65% or 40% |
| Largest motor | Standard method only. | Add 25% of it |
| Hot tub, sauna | Specific loads go in at full value. | 100% of the rating |
What size electrical service does a house need?
Divide the calculated load by 240 V and round up to the next standard rating. A one family home needs at least 100 A, and most new homes go in at 200 A.
| Service | Capacity at 240 V | Typical home | Usually carries |
|---|---|---|---|
| 60 A | 14,400 W | Small, built before 1960 | Gas appliances only, not allowed in new homes |
| 100 A | 24,000 W | Under 1,500 sq ft | Gas heat, electric dryer, basic cooling |
| 150 A | 36,000 W | 1,500 to 2,500 sq ft | Central air, electric range and dryer, tight with a charger |
| 200 A | 48,000 W | 2,000 to 4,000 sq ft | All electric with heat pump, charger, hot tub |
| 320 A | 76,800 W | Over 4,000 sq ft | Several HVAC zones, pool, workshop |
| 400 A | 96,000 W | Over 5,000 sq ft | Two 200 A panels or CT metering |
How many watts do common home appliances use?
Running watts drive your energy use and your bill. Nameplate VA is what a load calculation counts. Your appliance label beats both, so use it when you have it.
| Appliance | Typical running watts | Load calculation rating |
|---|---|---|
| LED bulb (100 W equivalent) | 13 W | Inside the 3 VA per sq ft |
| Ceiling fan | 35 W | Inside the 3 VA per sq ft |
| Refrigerator | 225 W | 900 VA |
| Microwave oven | 1,500 W | 1,500 VA built in |
| Dishwasher | 330 W | 1,200 VA |
| Clothes dryer | 2,790 W | 5,000 VA |
| Water heater, 40 gallon | 4,500 W | 4,500 VA |
| Electric range or oven | Varies with burners in use | 8,000 VA |
| Central air conditioner | Varies with size | 4,000 VA |
| Level 2 EV charger | Charger rating while charging | 7,680 to 14,400 VA |
A refrigerator runs about a third of the time it is plugged in, so 8 hours a day is a fair input in the energy tab.
What changes a home's calculated load?
Two houses of the same size can land a full service size apart. These are the inputs that swing it most.
| Factor | What changes | Typical effect |
|---|---|---|
| Method | The optional method's single 40% factor usually lands lower. Same 2,900 sq ft home: | 198 A standard, 142 A optional |
| Existing or new | An existing home keeps a smaller block at full value. | 8,000 or 10,000 VA at 100% |
| Heating fuel | Gas heat drops out. Electric heat competes with the air conditioner for one line. | Larger of heat or cool only |
| EV charger size | Bigger chargers add more, and they run for hours. | 7,680 to 14,400 VA |
| Tankless water heater | The biggest single load a house can add. A 27 kW unit alone: | About 112 A |
| Square footage | Cheap on paper. 500 more sq ft adds 1,500 VA before demand factors. | About 525 VA after the 35% |
| Gas to electric | Switching the range or dryer adds its full rating to the list. | 8,000 VA range, 5,000 VA dryer |
| Load management | Pauses the EV charger while the house is busy. A subpanel adds breaker spaces, not capacity. | Often enough on 200 A |
How do electricians do a load calculation for a panel upgrade?
The math is quick. What takes time is getting real nameplate figures instead of guesses, because the permit and the inspector work from the same sheet.
- Read the nameplatesRange, dryer, water heater, air handler, condenser and any charger the customer has bought. Photos on the first visit save a second trip.
- Measure the living areaOutside dimensions. Skip open porches and garages.
- Pick the methodThe optional method needs a single 120/240 V service of 100 A or more. Below that, or on a three phase service, use the standard method.
- Apply the demand factors8,000 VA for an existing home, 10,000 VA for a new one, then 40% of the rest.
- Add heating or coolingWhichever is larger, at the percentage that fits the equipment. A heat pump with backup strips counts the compressor plus 65% of the strips.
- Round up and file itDivide by 240 V, pick the next standard size and attach the sheet to the permit.
The Size the service tab runs these steps and prints the result on one page.
Electricians: EV charger and panel upgrade leads call while you are inside a panel.
A homeowner who just bought a charger rings three electricians and books whoever picks up. ServiceAgent answers every call, asks what panel they have and what they want to add, books the load calculation visit on your calendar and texts the confirmation, so the upgrade job stays yours.
Book a free demoFrequently asked questions
Short answers on home electrical load, panel capacity and what the numbers in this calculator mean.
Book a free demoHow do I calculate my electricity load?
Multiply the living area by 3 VA, add 1,500 VA for each small appliance and laundry circuit, then add the nameplate rating of every fixed appliance. Apply the demand factors, add the larger of heating or cooling, and divide by 240 to get amps.
How do I find my home's total load in kW?
Load calculations are written in volt amperes, and residential worksheets treat one VA as one watt for these loads. Divide the total VA by 1,000. A 25,928 VA result is about 25.9 kW, or 108 A at 240 V.
How much electricity does 3,000 watts use in 1 hour?
3 kWh. Multiply watts by hours and divide by 1,000. The Daily energy use tab does the same for every appliance you list.
How do I calculate AC load in kW?
Take the wattage from the unit's nameplate and divide by 1,000. If the label only lists amps, multiply the amps by the voltage first, so 20 A at 240 V is 4,800 W, or 4.8 kW.
What is the difference between connected load and demand load?
Connected load is everything added up as if it all ran at full power at once. Demand load applies the code's demand factors, because a range, dryer and water heater rarely peak together, so it is always lower.
Which demand factor should I use in an electrical load calculator?
Use the one the code sets for your method instead of a guess. The optional method uses 100% of the first 8,000 VA in an existing home or 10,000 VA in a new one and 40% of the rest. The standard method takes the first 3,000 VA of lighting at 100% and the rest at 35%, and fixed appliances at 75% when there are four or more.
Does this calculator size the wire and breakers?
It gives the calculated amps and the minimum standard service rating. Conductor size, breaker selection and any local amendments are for a licensed electrician to confirm.
Can I use the result to size a generator?
Yes, as the starting point. Add up only the circuits you want during an outage, then allow for motor starts: one common rule is to double the largest motor load for the startup surge.
Should I leave room for future loads?
Many electricians add 25% to the calculated amps before choosing a size. The code does not require it, but it is cheaper than a second upgrade when a second charger or a heat pump arrives.
Does power factor matter for a home?
Power factor is real power in kW divided by apparent power in kVA. Homes are billed on kWh, so it matters most for sizing generators, transformers and UPS units, where the kVA rating is the limit.
What does a panel upgrade cost if the calculation says I need one?
Going from 100 A to 200 A typically runs $1,500 to $4,000, with permits adding $100 to $500. If the utility has to replace the transformer or service drop, it can reach $5,000 to $8,000. The electrical cost calculator prices the job for your state.
Leads growth and product marketing for ServiceAgent at SaaS Labs, where he has worked in product marketing since 2020. Writes ServiceAgent's coverage of AI call answering, CRM and home services operations.
IBEW Local 134 Journeyman Electrician with 18 years of residential and commercial experience. Reviews electrical content and panel upgrade pricing for ServiceAgent.
Published by ServiceAgent, the AI front office for home service teams. Planning estimate only. The result depends on the real nameplate ratings in the home and the code edition your area has adopted. A licensed electrician must confirm the load calculation before any service or panel work.