Power Totals

Independent electrical planning tools

Electrical calculations, laid out like a workbench.

Calculate wire, power, energy cost, battery, solar, transformer, motor, and circuit relationships without an account or sign-up wall.

Source, conductor, and load relationshipA simplified 240 volt source sends 20 amps through a conductor with a 2 volt drop to a 238 volt load using 4.76 kilowatts.FIELD PATH / 01SOURCE240 V20 A2 V DROPLOAD238 VP = V × I238 V × 20 A = 4.76 kW
Source voltage, conductor drop, and load power shown as one traceable path.

Tool directory

Choose a calculation path

Six benches, organized by the electrical relationship you need to solve.

Wire & voltage

Conductor geometry, resistance, voltage drop, and voltage-drop-only selection.

4 tools
Voltage Drop CalculatorCalculate resistive voltage drop, delivered voltage, conductor resistance, and I²R loss for DC, single-phase, or three-phase circuits.Wire Size by Voltage Drop CalculatorFind the smallest supported AWG conductor that meets your editable voltage-drop target using a transparent resistance model.AWG to mm² CalculatorConvert American Wire Gauge to diameter, cross-sectional area, and circular mils, or find the nearest AWG for a metric area.Wire Resistance CalculatorEstimate conductor resistance, resistance per length, voltage loss, and heat loss from material, size, length, and temperature.

Power & phase

DC, single-phase, three-phase, real, apparent, and reactive power relationships.

7 tools
Watts to Amps CalculatorConvert watts to current for DC, single-phase AC, and three-phase AC with explicit power factor.Amps to Watts CalculatorConvert current to real power for DC, single-phase AC, and balanced three-phase AC.kW to Amps CalculatorConvert kilowatts to current for DC, single-phase, or balanced three-phase systems.kVA to Amps CalculatorConvert apparent power in kVA to current for single-phase or balanced three-phase systems.Single-Phase Power CalculatorCalculate real power, apparent power, and current for a single-phase AC circuit.Three-Phase Power CalculatorCalculate real and apparent power from line voltage, current, and power factor in a balanced three-phase system.Power Factor CalculatorCalculate power factor, reactive power, and phase angle from real and apparent power.

Battery & energy

Energy cost and usage, battery runtime, bank layout, inverter loads, EV charging, and DC cable-loss planning.

6 tools
Battery Runtime CalculatorEstimate ideal and adjusted runtime from battery energy, load, usable depth, and conversion efficiency.Electricity Cost CalculatorCalculate electricity cost from energy use, billing-period length, and your own price per kilowatt-hour.Appliance Running Cost CalculatorEstimate appliance energy use and operating cost from wattage, daily runtime, days, and your electricity rate.kWh CalculatorConvert watts and operating time into watt-hours and kilowatt-hours for one or more identical loads.EV Charging Cost CalculatorEstimate EV charging energy, time, and cost from battery capacity, charge change, efficiency, charger power, and your rate.Energy Usage CalculatorAdd multiple appliances to estimate daily and period energy use plus cost at your entered electricity rate.

Solar

Local solar production, panel-count, storage, off-grid, RV, savings, and payback planning with dated static data. Browse the grouped Solar hub

17 tools
Battery Bank CalculatorCalculate series/parallel battery quantity, bank voltage, amp-hours, and watt-hours from unit specifications.Inverter Size CalculatorAggregate running and surge loads, then apply your own headroom and efficiency assumptions.Solar Cable Voltage Drop CalculatorCalculate resistive DC voltage drop and cable power loss between solar-system components.How Many Solar Panels Do I Need CalculatorEstimate solar system size, panel count, annual production, and roof area from energy use, ZIP, panel watts, orientation, and shading.Solar Battery CalculatorEstimate solar battery energy, amp-hours, autonomy, and a series-parallel unit count from daily use and visible storage assumptions.Off-Grid Solar CalculatorAggregate daily loads to estimate off-grid solar array power, battery storage, bank amp-hours, and charge-controller current.RV Solar CalculatorEstimate an RV solar array, battery storage, bank amp-hours, and controller current from an editable list of travel loads.Solar System Size CalculatorEstimate required solar array kW and annual production from monthly energy use, ZIP, orientation, shading, and visible loss assumptions.Solar ROI CalculatorEstimate solar production first, then show dated simple ROI, payback, and net savings from visible cost, rate, escalation, and degradation inputs.Solar Savings CalculatorEstimate annual solar production, first-year bill offset, and long-term simple savings from visible usage, system, rate, and degradation inputs.Solar Payback CalculatorEstimate solar production independently, then calculate simple payback from visible installed cost, energy use, rate, escalation, and degradation.Solar Panel Angle CalculatorEstimate a fixed or seasonal solar-panel tilt from latitude and compare the direct-beam geometry at an entered installation angle.Solar Charge Controller CalculatorCalculate minimum controller charge current and cold-weather PV input voltage from array watts, panel Voc, series count, temperature, and bank voltage.Portable Power Station CalculatorEstimate portable power-station capacity, runtime, and recharge time from an AC load, daily hours, trip length, usable efficiency, and charging input.Solar Loan CalculatorEstimate a solar loan payment, dealer-fee-adjusted principal, total payments, bill comparison, and an optional verified principal lump sum.Solar Lease vs Buy CalculatorCompare nominal 25-year cash, loan, lease, PPA, and utility-baseline payments from visible user assumptions.Commercial Solar CalculatorEstimate commercial solar production, first-year energy value, operating value, and an optional user-confirmed MACRS depreciation scenario.

Transformers & motors

Ideal transformer relationships, motor current estimates, and generator load aggregation.

4 tools
Transformer kVA CalculatorCalculate transformer current from kVA and voltage for single-phase or balanced three-phase systems.Transformer Turns Ratio CalculatorCalculate ideal voltage, turns, and inverse current relationships between transformer windings.Motor Current EstimatorEstimate motor input current from mechanical output, voltage, phase, efficiency, and power factor.Generator Sizing & Load CalculatorSize a generator estimate from running and starting loads, then apply your own reserve and power-factor assumptions.

Technical utilities

Ohm's law, resistor networks, divider circuits, geometry, and LED resistor math.

5 tools
Ohm's Law CalculatorSolve voltage, current, resistance, and power from any sufficient pair of electrical values.Voltage Divider CalculatorCalculate two-resistor divider output, current, and the effect of an optional load resistor.Series & Parallel Resistor CalculatorCalculate equivalent resistance and basic branch values for a supported series or parallel resistor network.Conduit Fill Geometry CalculatorCalculate geometric occupied area and fill percentage from user-entered raceway and conductor diameters.LED Resistor CalculatorCalculate a series resistor and resistor dissipation for a simple string of LEDs.

Bench notes

Transparent by construction

Formulas shownSee the equations, units, assumptions, and rounding behind each result.

Not a code checkResults do not determine NEC or CEC compliance; verify applicable codes and local requirements.

Margins stay explicitSafety factors, derating, and reserve margins are shown separately from calculated loads.