"Do I need a 200-amp panel?" is the question every electrician hears on the first home visit. The honest answer comes from a load calculation per NEC Article 220 — not a guess based on house size or neighbors. Here is what goes into the math.

Standard vs Optional method

NEC 220 gives two methods for sizing a residential service:

  • Part III "Standard": sum each load with its own demand factor. Conservative, line-itemy, and the method this calculator uses.
  • Part IV "Optional": 100% of the first 10 kVA + 40% of the remainder. Plus AC vs heat at the larger of the two. Usually gives a smaller answer than Standard for all-electric homes.

Either is code-legal. Standard is what inspectors see most often and what plan reviewers expect on a residential service-upgrade permit.

The pieces of a Standard load calc

General lighting + receptacles. NEC 220.41: 3 VA per ft² of habitable area. A 2,000 ft² house contributes 6,000 VA right off the top.

Small-appliance circuits. NEC 210.11(C)(1): at least 2 in the kitchen + dining; each adds 1,500 VA.

Laundry circuit. 1,500 VA for the dedicated laundry receptacle (not the dryer itself — that is its own load).

Lighting demand factor. NEC 220.42 lets you take 100% of the first 3,000 VA of lighting+SA+laundry, then 35% of the next 117,000 VA. That is the discount that keeps panel calcs reasonable.

Range. NEC 220.55 + Table — an 8 kW to 12 kW range counts as 8,000 VA flat. Each 1 kW over 12 adds 5% to that 8,000.

Dryer. NEC 220.54 — 5,000 VA minimum, or nameplate if higher.

Water heater, AC, EV, heat pump, hot tub.Nameplate VA. AC vs heat takes the larger of the two (220.60); they don't run at the same time. EV charging is continuous so it gets the 1.25 multiplier built in.

What "200 amps is enough" actually means

A 200 A service at 240 V can deliver 48 kVA continuous. After load calc, most 2,500-3,500 ft² homes with a mix of gas + electric land between 100 A and 160 A calculated demand — 200 A is comfortable.

Where 200 A starts feeling tight:

  • All-electric (heat pump + induction range + heat-pump water heater + heat-pump dryer + EV) on a 3,000+ ft² house
  • Two EV chargers (a 48 A + a 32 A is 96 A continuous, sized to 120 A — that alone is 60% of the panel)
  • Hot tub + pool heater + workshop subpanel
  • Whole-home Generac standby with priority interlock — fine, but factor it

Run your numbers through the panel load calculator before committing to a service size on a remodel.

Service sizes that exist

  • 100 A — older homes, small homes, gas-heat + gas-cooking up to about 1,200 ft². Common upgrade target.
  • 150 A — middle ground, cheap if the meter base supports it.
  • 200 A — the residential default since the 1990s.
  • 320 A / 400 A "class 320" meter — two 200 A panels off one meter, the heavy-electrification target. Many utilities are pushing customers here on new builds.
  • 600+ A — engineered, multi-family or commercial.

Common load-calc mistakes

Counting both AC and heat. NEC 220.60 says take the larger of the two; they don't run together. Counting both inflates the load by 30-40%.

Forgetting the EV 125%. EV charging is continuous. A 7.7 kW (32 A × 240 V) charger contributes 9,625 VA to the load, not 7,700. The calculator handles this; spreadsheet versions often miss it.

Skipping the lighting demand factor. 220.42 gives a real discount. Do not add 100% of every lighting + SA + laundry circuit straight through — you will spec a 320 A service when 200 A is correct.

Estimate only. The panel load calculator uses the NEC 220 Part III Standard method with typical single-phase 240/120 V residential assumptions. It does not handle 3-phase, multifamily, dwelling unit feeders to separate buildings (220.84), or unusual loads. A licensed electrician must run the full Part III/IV worksheet for any permit submittal.