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Calculator collection · 22 distinct tools

Electrical & Engineering Calculators

Solve foundational voltage, current, resistance and power relationships without hiding the formulas.

Electrical pages separate real power, apparent power, current, voltage, power factor, efficiency and ideal component relationships. Formula results are calculation aids—not conductor, breaker or code-compliance recommendations.

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Open a real interactive tool instead of landing on a thin keyword page.

Working shown

Formulas, units and assumptions stay visible beside the result.

Deep topic cluster

Move between genuinely different calculations inside one collection.

Limits stated

Supplier, manufacturer, drawing and standards data remain authoritative where required.

Choose the calculation that matches the job

Each page owns a distinct input/output task. Reciprocal forms stay together when the underlying job is the same.

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Ohm's Law Calculator — Volts, Amps, Ohms and Watts

Calculate voltage, current, resistance and power from any two positive electrical values using Ohm's Law and Watt's Law.

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Watts to Amps Calculator — DC, Single-Phase and Three-Phase

Convert watts to amps from power and voltage for DC, single-phase AC or balanced three-phase AC, with an explicit power-factor input for AC loads.

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Amps to Watts Calculator — DC, Single-Phase & Three-Phase

Convert current in amps to real power in watts for DC, single-phase AC or balanced three-phase AC with explicit voltage and power-factor inputs.

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kW to Amps Calculator — DC, Single-Phase & Three-Phase

Convert kilowatts to amps from voltage, system type and power factor for DC, single-phase AC or balanced three-phase AC.

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Electricity Cost Calculator — kWh & Energy Cost

Estimate energy use in kWh and simple electricity cost from device watts, hours per day, number of days and your own tariff per kWh.

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Power Factor Calculator — kW, kVA & kVAR

Calculate power factor from real power and apparent power, or derive kVA and reactive power from kW and a known power factor.

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kVA to Amps Calculator — Single & Three Phase

Convert apparent power in kVA to current using voltage and phase configuration, with separate balanced three-phase line-to-line and line-to-neutral voltage formulas.

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Three-Phase Power Calculator — kW, kVA, kVAR & Power Factor

Calculate balanced three-phase apparent, real and reactive power from line-to-line voltage, current and power factor, with phase angle shown for the simplified power triangle.

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VA to Watts Calculator — Apparent vs Real Power

Convert volt-amperes to watts or watts to VA using an explicit power factor, while keeping apparent power and real power separate instead of treating them as interchangeable.

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kW ↔ kVA Calculator — Real & Apparent Power

Convert kW to kVA or kVA to kW with an explicit power factor, plus a reverse check that keeps real and apparent power from being treated as the same quantity.

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Horsepower to Amps Calculator — DC, 1-Phase & 3-Phase

Convert electric horsepower output to estimated input current using voltage, efficiency, phase and power factor, with the input watts and assumptions shown beside the result.

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Ah ↔ Wh Calculator — Battery Charge & Energy

Convert amp-hours to watt-hours or watt-hours to amp-hours using battery voltage, with kWh and mAh equivalents and a reverse check on the same page.

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Battery Runtime Calculator — Wh/Ah, Load, DoD & Efficiency

Estimate battery runtime from Wh or Ah capacity, voltage, load, usable depth of discharge and conversion efficiency, while keeping ideal and adjusted runtime separate.

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Series & Parallel Resistor Calculator — Equivalent Resistance

Calculate equivalent resistance for up to four resistors in series or parallel, with reciprocal working shown and an optional source voltage for total current.

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Series & Parallel Capacitor Calculator — Equivalent Capacitance

Calculate equivalent capacitance for up to four capacitors in series or parallel, with the reciprocal relationship and optional stored-energy estimate from an entered voltage.

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Frequency ↔ Period Calculator — Hz, kHz, MHz, Seconds & More

Convert frequency to period or period to frequency with explicit Hz/kHz/MHz/GHz and s/ms/µs/ns units, reciprocal working, cycles-per-minute context and a reverse check.

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Joules ↔ Watt-Hours Calculator — J, kJ, MJ, Wh & kWh

Convert joules to watt-hours or watt-hours to joules using the exact 3,600 J per Wh relationship, with kJ, MJ, Wh and kWh equivalents plus visible reciprocal working.

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kWh ↔ MJ Calculator — Kilowatt-Hours & Megajoules

Convert kilowatt-hours to megajoules or megajoules to kilowatt-hours with the exact 1 kWh = 3.6 MJ relationship, plus joule, kilojoule and watt-hour equivalents.

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Transformer Turns Ratio Calculator — Solve Voltage or Winding Turns

Solve an ideal transformer for primary voltage, secondary voltage, primary turns or secondary turns from the other three values, with turns ratio, voltage ratio and ideal current-ratio context.

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Transformer kVA Calculator — Single & Three-Phase Current

Calculate transformer kVA from voltage and current or calculate ideal primary and secondary full-load current from a kVA rating, with single-phase and balanced three-phase formulas kept explicit.

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RC Time Constant Calculator — Solve τ, R or C + Cutoff & Timing

Calculate RC time constant from resistance and capacitance or solve backward for resistance or capacitance from a target tau, with five-tau settling, first-order cutoff and charge/discharge timing.

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LED Resistor Calculator — E12/E24 Value, Color Code & Power

Calculate a simple DC LED current-limiting resistor, round upward to E12/E24, recalculate actual current and power, and show the selected resistor’s standard 4-band color code.

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Useful next calculations

Move to a different formula only when the next question actually changes.

Explore adjacent calculator collections

Cross-cluster links help you move from measurement to project quantity, electrical relationships, math or media planning without flattening everything into one giant list.

Formula first, assumptions visible

MAXScanner keeps editable rates and dimensions next to the result, shows the working where it helps, and avoids turning reciprocal formulas into duplicate pages. For product, electrical or construction decisions, manufacturer data, drawings and applicable standards remain authoritative.