Power Consumption Calculator

• Single-phase AC real power: P = V × I × PF
• Three-phase AC real power: P = √3 × V_LL × I × PF
• DC real power: P = V × I
• Apparent power: S = V × I (or √3 × V_LL × I for 3φ)
• Reactive power: Q = √(S² − P²) (AC only)
• Operating energy per day: E_op = (P/1000) × qty × hours × duty
• Standby energy per day: E_sb = (P_sb/1000) × qty × (24 − hours)
• Monthly energy: E_month = (E_op + E_sb) × days
• Monthly cost: Cost = (E_month × rate) + (peak kW × demand charge) + PF penalty

1. Enter your electricity rate, currency label, and optional demand and emissions factors.
2. Add one or more load rows. Choose supply type (1φ AC, 3φ AC, or DC).
3. Fill voltage, current, power factor (AC only), quantity, and operating schedule.
4. Use duty cycle to model intermittent loads. Add standby watts for idle periods.
5. Press Calculate to show results below the header.
6. Use CSV/PDF to document results for audits or sharing.

Load characterization and duty cycle

Start with measured RMS voltage and current, or nameplate data. Motors, welders, and compressors rarely run at 100% continuously, so duty cycle is the safest way to represent intermittent demand. A 6 A compressor at 400 V and 0.88 PF draws about 3.65 kW when loaded, but at 60% duty its average operating power falls to about 2.19 kW. Use quantity to scale identical assets and keep hours per day within realistic shifts.

Single-phase, three-phase, and DC modeling

The calculator separates 1φ AC, 3φ AC, and DC so the same inputs produce comparable real power outputs. For 3φ systems, line-to-line voltage with the √3 factor converts current into apparent power, then PF converts it into real power. This is critical when comparing kW to kVA for generator sizing, cable selection, and transformer loading. Typical industrial PF ranges from 0.75–0.95 without correction; DC is treated as PF = 1 by definition.

Standby and always-on losses

Small standby loads accumulate quickly because they persist when production stops. A controller consuming 15 W overnight adds 0.015 kWh each hour; over 21 non-operating hours that is 0.315 kWh per day per unit. Multiply by 30 days and several units and it becomes a visible line item. Enter standby watts for drives, PLCs, network gear, and chargers to avoid underestimating monthly energy.

Energy, emissions, and cost forecasting

Energy is computed from power and time, then rolled up to daily, monthly, and yearly totals. Cost uses your kWh rate plus optional demand charges based on estimated peak kW. Many tariffs also add surcharges when average PF drops below a threshold; the penalty input models this as a percentage of the monthly bill for quick scenario testing. Emissions are reported using a user-provided kg CO₂ per kWh factor for sustainability dashboards.

Verification and reporting discipline

Treat results as engineering estimates and validate them against meter data whenever possible. Check units: watts for instantaneous power, kWh for consumption, and kW for demand. If a single load dominates peak kW, revisit duty cycle and standby assumptions. Export CSV for spreadsheets and PDF for approvals so reviewers can trace inputs, formulas, and per-load contributions.

Can I use nameplate kW instead of current?

Yes. Convert kW to current using I ≈ (kW×1000)/(V×PF) for 1φ, or I ≈ (kW×1000)/(√3×VLL×PF) for 3φ. When unsure, enter measured current for better accuracy.

Which voltage should I enter for three‑phase loads?

Enter line‑to‑line voltage (VLL), such as 400 V or 480 V. The calculator applies the √3 factor internally. Do not enter phase‑to‑neutral voltage unless your current measurement matches that basis.

How do hours/day and duty cycle work together?

Hours/day is the scheduled operating window. Duty cycle is the percentage of that window where the load actually draws near its rated current. Example: 8 hours at 60% duty models about 4.8 effective hours.

Why is power factor ignored for DC?

Power factor describes the phase relationship between voltage and current in AC circuits. In DC there is no phase shift, so real power is simply V×I and PF is treated as 1.

How is peak demand (kW) estimated?

Peak kW is estimated per load as real power × duty plus standby, scaled by quantity. The calculator reports the maximum single‑load peak as a conservative demand indicator. Sites with many concurrent loads may need interval meter data.

What should I use for the emissions factor?

Use your utility’s published kg CO₂ per kWh value, or a trusted regional grid average. If you only need a rough estimate, try 0.40–0.70 kg CO₂/kWh, then refine later with official data.