Reactive Power Estimator
Explore how motors, compressors, and transformers in your home create reactive power — the invisible energy that flows but does no work.
Your Electric Bill
Inductive Appliances in Your Home
Select every motor-driven appliance you use regularly. Each creates reactive power.
Power Factor Analysis
Power Breakdown
Real power (useful work) vs. reactive power (oscillation)
Appliance Reactive Contribution
Which appliances create the most reactive power
Important Context: Residential Billing
Residential electric meters in North America bill by kilowatt-hour (kWh) — which measures real power, not apparent power. According to the National Institute of Standards and Technology (NIST), power factor correction devices reduce current but do not reduce the kWh registered by a residential meter. The physics of reactive power is real and well-established since Charles Steinmetz's work in 1893, but bill savings from plug-in correction devices apply primarily to commercial and industrial customers who face power factor penalties. This tool is designed to educate — not to promise savings.
Commercial / Industrial
PFC saves moneyLarge facilities are billed on demand (kVA) or face explicit power factor penalties when PF drops below 0.85–0.90. A factory running heavy motors at PF 0.70 pays a surcharge because the utility must supply more current than the meter's kWh reading reflects.
- Billed by kVA demand — apparent power matters
- Power factor penalties (typically below 0.85 PF)
- Capacitor banks sized by engineers, installed at the panel
- ROI measured in months, savings verified by utility billing
- Standard practice since the 1920s — billions saved industry-wide
Residential
No bill savingsHomes are billed by kWh (kilowatt-hours) — a measure of real power only. Your meter ignores reactive power entirely. A capacitor reduces current drawn from the line, but your meter measures watts × hours, which stays the same.
- Billed by kWh — only real power is metered
- No power factor penalty on residential tariffs
- Plug-in devices reduce current, not kWh
- NIST confirmed: bill "remains the same — with or without the device"
- ENERGY STAR does not certify any residential PFC device
| Factor | Industrial / Commercial | Residential |
|---|---|---|
| Billing unit | kVA demand + kWh | kWh only |
| PF penalty? | Yes (below 0.85–0.90) | No |
| Meter type | Demand meter (tracks kVA peak) | Energy meter (tracks kWh consumed) |
| Correction method | Engineered capacitor banks at service panel | N/A — no financial benefit |
| Typical ROI | 3–18 months | $0 saved (per NIST) |
| Why it works / doesn't | Lower kVA demand = lower demand charges + avoided penalties | Lower current does not change kWh reading |
The Key Distinction
When a capacitor corrects power factor, it reduces the current flowing from the utility. For an industrial customer billed on kVA demand, less current = lower bill. For a homeowner billed on kWh, the math is different: kWh = Volts × Amps × Power Factor × Hours. The capacitor lowers Amps but raises Power Factor by the same proportion — the product stays identical, and so does your bill.
Sources: NIST, "Demystifying Power Factor Correction Devices" (2009) — M. Misakian, T. Nelson, W. Yarbrough. ENERGY STAR statement on PFC devices. FTC "Notice of Penalty Offenses Concerning Energy Saving Claims" (1979).