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Search by task, unit, voltage, or equipment. Every result opens a calculator with the formula and assumptions shown.
Live example
See a voltage drop result right now
Realistic defaults are already loaded. Inspect the result first, then change any input.
Calculated result
Calculated voltage drop
1.998 V · 1.665%
Within your editable planning target
- Delivered voltage
- 118.002 V
- Path resistance
- 0.09988 Ω
- Power loss
- 39.954 W
Planning result only; verify ampacity, protection, installation method, and local rules separately.
All calculators
Choose a calculation path
Six focused groups, organized around the electrical relationship you need to solve.
Wire & voltage
Conductor geometry, resistance, voltage drop, and voltage-drop-only selection.
Voltage Drop CalculatorCalculate voltage drop in volts and percent, voltage at the load, conductor-path resistance, and I²R loss for DC, single-phase, or balanced 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.
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.
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.Home Backup Power CalculatorPlan battery, inverter, solar, and generator capacity from editable critical loads, outage duration, efficiencies, reserve, and optional recharge.Battery Charging Time & C-Rate CalculatorCalculate battery charging time, charger current or power, C-rate, source energy, and cost using amp-hour or kilowatt-hour capacity.EV Home Charging PlannerPlan EV home charging from daily distance, vehicle efficiency, overnight hours, charger power, charging losses, battery state of charge, and 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
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.Solar Panel Calculator: How Many Panels Do You Need?Estimate how many solar panels you need, required system size, annual production, and nominal panel area from monthly energy use or a bill, ZIP, panel watts, roof 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.Solar Panel String & MPPT CalculatorCheck a solar panel series/parallel layout from module values, temperature, MPPT voltage, maximum PV voltage, and inverter or controller input-current limits.Plug-In Solar Savings CalculatorEstimate balcony and plug-in solar savings from panel power, local yield, shade, self-consumption, electricity rates, and upfront cost with no tax credit.Virtual Power Plant Value CalculatorCompare a virtual power plant offer using annual payments, battery event energy, recharge costs, wear allowance, and fees to estimate net annual value.
Transformers & motors
Ideal transformer relationships, motor current estimates, and generator load aggregation.
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.Generator Fuel Consumption & Runtime CalculatorCalculate generator fuel consumption, runtime, outage fuel, and cost from explicit manufacturer or measured fuel-use data.
Technical utilities
Ohm's law, resistor networks, divider circuits, geometry, and LED resistor math.
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.
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Contractor directory
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Choose your project, compare companies serving the area, then contact the contractor directly.
01EV charger installersFind electricians for EV charger installation, including Level 2 chargers, hardwired units, 240V outlets, and load management.02Electrical panel upgrade contractorsFind electricians for panel replacement, service upgrades, subpanels, and capacity projects for EV charging, solar, or home electrification.03Solar installersCompare rooftop or ground-mounted solar installation, electrical integration, and utility coordination.04Battery backup installersFind contractors for home batteries, backup circuits, and storage integration.05Generator installersCompare standby generator installation, transfer equipment, and backup-power services.06Wiring and circuit electriciansFind electricians for rewiring, new wiring, and dedicated electrical circuits.07Lighting installersFind electricians for lighting installation, fixture upgrades, and indoor or outdoor lighting.
Popular metro areas
Open the full directoryChicago, ILChicago22Washington D.C., DCWashington D.C. area17San Jose, CASan Jose–Silicon Valley14San Francisco, CASan Francisco area13Austin, TXGreater Austin12Houston, TXHouston area12Bakersfield, CABakersfield area11Atlanta, GAMetro Atlanta10Phoenix, AZPhoenix10Sacramento, CASacramento10
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How results work
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PowerTotals helps with planning. Final equipment, conductor, protection, permit, and installation decisions belong with qualified professionals and local authorities.
01Formulas shownSee the equations, units, assumptions, and rounding behind each result.
02Not a code approvalResults do not determine NEC or CEC compliance. Verify the rules that apply locally.
03Margins stay explicitSafety factors, derating, and reserve margins remain separate from calculated loads.