Power and Energy Calculators
Maximum demand, energy cost, electricity bill, power factor and reactive power correction calculators with formulas, assumptions and examples.
Use these to turn a connected load into a demand figure, to cost energy, and to deal with power factor. Maximum demand takes a connected load through demand and diversity factors to a design load in kW and kVA. The power factor tools convert between real, apparent and reactive power and size a correction capacitor bank. The cost tools estimate what one appliance, or a whole bill, will cost.
Where to start
- Maximum Demand: Connected load to maximum demand in kW and kVA, the usual first step in sizing supply equipment.
- Power Factor Correction: Capacitor kVAR needed to raise the power factor to a target.
- Appliance Running Cost (Energy and Cost): Running cost of one appliance per day, month and year.
- Electricity Bill from Tariff Slabs (fixed charge, tax): A whole-bill estimate from tariff slabs, a fixed charge and tax.
All 12 calculators in this category
Power Factor
- kW to kVA and kVAR: Convert real power to apparent and reactive power.
- kVA to kW: Real and reactive power from apparent power and power factor.
- Power Factor: Power factor from real and apparent power.
Capacitors and Reactive Power
- Power Factor Correction: Capacitor kVAR needed to raise power factor to a target. Open in Elecmetric
- Capacitors in Series and Parallel: Combined capacitance of three capacitors, both ways. Open in Elecmetric
- Capacitor Bank Size (µF): Capacitance per phase and line current for a delta-connected bank of a given kVAR. Open in Elecmetric
Power and Energy
- Appliance Running Cost (Energy and Cost): Running cost of one appliance or load: energy and cost per day, month and year, and over the days you choose, from its power, how hard it runs, hours of use and one flat tariff. For a whole bill with slabs, a fixed charge and tax use Electricity Bill from Tariff Slabs.
- Electricity Bill from Tariff Slabs (fixed charge, tax): Whole-bill estimate from the units on your meter: up to three tariff slabs, a fixed charge and tax. To cost one appliance, use Appliance Running Cost.
- kWh to kW and Watts: Average power from energy used and the time it took.
- Watts, Joules, kWh and Time (any two): Enter any two of power, energy and time. The third is calculated: watts to joules, joules to watts, kW to kWh, watts to kWh.
- mAh to Wh and Wh to mAh: Battery capacity in mAh, energy in Wh and nominal voltage: enter any two and the third is calculated.
- Maximum Demand: Coincident maximum demand from connected load, demand factor and diversity factor. Open in Elecmetric
What these calculators do not cover
Demand factors, diversity factors, tariffs and tax rates are inputs you supply, and the defaults are examples only. Use the factors from your project specification, local code or utility tariff. Power factor correction here is a simple kVAR calculation and does not model harmonics or resonance with the supply.
Cross-check: all 12 calculators listed here are compared with 185 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.
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