Circuits And Components
Series and parallel circuit calculators for voltage dividers, resistor networks, LED series resistors, shunts, reactance, capacitors, RC timing, and voltage-drop checks.
Electrical Formulas
Voltage, current, resistance, power, energy, power factor, and cost calculators for basic electrical math.
Subcategories
Power, Energy And Cost
Power factor, reactive power, kWh use, time-of-use cost, fuel cost, and energy savings calculations.
Voltage, Current And Resistance
Ohm law, watts, amps, volts, resistance, current, voltage, and DC power calculations.
Published Calculators
Current Limiting Resistor Calculator
Calculate DC series resistance, resistor voltage, and resistor power for a target current using entered supply and load voltage.
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Current From Power And Voltage Calculator
Calculate current in amps from entered power and voltage; AC phase, power factor, inrush, and protection decisions remain separate.
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Control Circuit Fuse Calculator
Calculate control load current, inrush reference current, and entered fuse-rating margins without selecting or approving a fuse.
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Control Relay Contact Load Calculator
Calculate relay contact VA, utilization, and remaining entered rating from contact voltage, contact current, and VA rating.
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Control Cable Shield Calculator
Calculate control-cable shield loop resistance, voltage drop, and dissipation from entered length, resistance, and current.
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Contactor Coil VA Calculator
Calculate steady-state VA, inrush VA, inrush ratio, and inrush excess for an entered contactor coil.
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Carbon Emissions from Electricity Calculator
Calculate electricity-related CO2e in pounds, short tons, and metric tons from measured energy use and an entered emissions factor.
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Battery Energy Cost Calculator
Calculate usable energy, charging energy, annual delivered energy, and cycling cost from battery capacity, efficiency, cycles, and energy rate.
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Annual Equipment Energy Calculator
Calculate daily and annual energy, annual cost, and average power from equipment wattage and operating schedule.
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AC Watts From Voltage And Current Calculator
Calculate single-phase AC active power in watts from RMS voltage, RMS current, and power factor.
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AC VA From Voltage And Current Calculator
Calculate single-phase AC apparent power in VA from RMS voltage and RMS current.
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24 VDC Control Voltage Drop Calculator
Estimate 24 VDC control-circuit voltage drop, load voltage, and margin against a documented minimum load voltage.
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AC Circuit Current Calculator
Calculate single-phase or balanced three-phase AC line current from real power, RMS voltage, power factor, and phase model.
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Thevenin Equivalent Calculator
Enter the Thevenin voltage, Thevenin resistance, and load resistance to evaluate source loading, terminal voltage, and resistive power.
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RMS Current Calculator
Calculate RMS current from a sine-wave peak, verified waveform factor, equally spaced samples, or separate AC and DC components.
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RMS Voltage Calculator
Convert a measured or modeled peak voltage to RMS voltage; 0.7071 applies to a verified sinusoidal waveform.
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RL Time Constant Calculator
Enter resistance and inductance to calculate the first-order RL time constant and its five-time-constant settling reference.
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Parallel Resistor Value Calculator
Calculate the equivalent resistance of three fixed resistors in parallel for component-level circuit review. Final component selection still requires rated voltage, power, tolerance, and application checks.
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Resistor Power Rating Calculator
Evaluate resistor dissipation and a preliminary minimum wattage from the entered electrical values. Confirm the exact part's thermal, pulse, and maximum-working-voltage ratings before selection.
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Series Resistor Value Calculator
Calculate the equivalent resistance of three fixed resistors in series for component-level circuit review. Final component selection still requires rated voltage, power, tolerance, and application checks.
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RC Filter Cutoff Calculator
Calculate the ideal first-order RC corner frequency from resistance and capacitance. The result is circuit arithmetic, not a complete filter, EMC, equipment, or code approval.
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Power Dissipation Calculator
Enter voltage, current, and operating hours to calculate ideal electrical power and energy. Treat the result as a screening estimate, not a thermal design approval.
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PLC I/O Load Calculator
Enter repeatable PLC, I/O, communication, and field-device rows with manufacturer-supplied current data. Backplane and field-power budgets remain separate.
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Monthly Electricity Bill Calculator
Models a monthly electric bill from kWh, energy rate, demand charge, fixed charge, and taxes while keeping tariff-specific adjustments outside the result.
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