How to use this calculator
- Enter Home area in sq ft.
- Enter Fixed appliance load in W.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
NEC-style estimate: general load = sq ft × 3 VA, plus two 1,500 VA small-appliance circuits and one laundry circuit, plus fixed appliances — with demand factors applied, then ÷ 240 V for amps. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
Planning estimate — a licensed electrician performs the binding NEC Article 220 calculation.
Where this fits in the project
Electrical sizing works backwards from load: total demand sets service size, circuit amperage sets wire gauge, and conductor count sets conduit fill. HVAC equipment is sized from the BTU load, never from floor area alone.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the electrical load calculator:
- Wire Size Calculator — Load calculation determines required wire gauge.
- Conduit Fill Calculator — Total circuit load affects conduit fill planning.
- Recessed Lighting Calculator — Lighting fixtures contribute to total electrical load.
- HVAC Size Calculator — HVAC is a major contributor to home electrical load.
- Solar Panel Calculator — Solar panels offset electrical load from the grid.
- Water Softener Size Calculator — Water softeners are plumbing systems, separate from the electrical load.
Frequently asked questions
What size panel does a modern home need?
200 A has become standard — EV charging, heat pumps and induction ranges outgrow 100 A services quickly.
What is a demand factor?
Not all loads run at once, so NEC discounts portions of connected load — 40% beyond the first 10 kVA of general load.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.