Physics and Engineering

  • Electrical Energy Calculator
    Calculate electrical energy from power and time with E = P·t. Enter watts or kilowatts and seconds, minutes or hours to get joules, Wh and kWh.
  • Continuity Equation Flow Rate Calculator
    Solve the continuity equation A₁v₁ = A₂v₂ for fluid velocity and find volumetric flow rate Q = A·v in pipes and ducts instantly.
  • Atwood Machine Calculator
    Calculate the acceleration and cord tension of an Atwood machine from two masses and gravity. Fast, accurate physics calculator with worked example.
  • Elastic Collision Calculator
    Compute the final velocities of two objects after a 1D elastic collision from their masses and initial velocities. Conserves momentum and kinetic energy.
  • Appliance Amperage Calculator
    Calculate the amperage (current draw) of any appliance from its wattage and voltage. Use I = P / V to size circuits, fuses, and wiring safely.
  • Coefficient of Restitution Calculator
    Calculate the coefficient of restitution (e) from collision velocities or from drop and bounce heights. Free, instant physics calculator.
  • Speaker Impedance Calculator
    Calculate total speaker impedance for series or parallel wiring. Enter up to 4 speaker impedances in ohms to find the combined load on your amplifier.
  • Inverter Size Calculator
    Calculate the right inverter size in VA from your total load in watts and power factor, with a safety margin for surge headroom and reliable operation.
  • Amp Hours (Ah) Calculator
    Convert watt-hours to amp-hours instantly. Enter battery energy in Wh and voltage to find capacity in Ah and mAh using Ah = Wh / V.
  • EV Cost Per Mile Calculator
    Calculate the energy cost per mile of your electric vehicle from its efficiency (miles/kWh) and your electricity rate. See cost per 100 miles and trip cost.
  • Watts to Amps Calculator (Three Phase)
    Convert watts to amps for three-phase AC circuits. Enter power, line-to-line voltage and power factor to get line current in amperes instantly.
  • Resultant Vector Calculator
    Add 2 or 3 vectors by their X and Y components to find the resultant vector's magnitude and direction angle θ. Free, instant 2D vector addition.
  • Vector Magnitude Calculator
    Calculate the magnitude (length) of a 2D or 3D vector from its x, y, z components using |v| = √(x²+y²+z²). Fast and accurate.
  • Density Calculator (Mass and Volume)
    Calculate density from mass and volume with ρ = m/V. Supports grams, kilograms, cm³, mL, liters and m³. Get results in g/cm³ and kg/m³ instantly.
  • Watts, Volts, Amps & Ohms Calculator
    Solve for voltage, current, resistance or power from any two known values using Ohm's Law (V=IR) and the power equations P=VI, P=I²R, P=V²/R.
  • Whole Home Electricity Bill Calculator
    Estimate your whole-home electricity bill by adding up each device's kWh, then applying your per-kWh rate and fixed fee. Works in any currency.
  • Appliance Energy Cost Calculator
    Calculate how much an appliance costs to run per day, month, and year from its wattage, hours of use, days per week, and your electricity rate per kWh.
  • Solar Panel System Size Calculator
    Estimate the solar PV system size (kW) and number of panels you need from your daily energy use, peak sun hours, performance ratio and panel wattage.
  • Solar System Size Calculator
    Estimate the solar PV system size (kW) you need from your monthly kWh use, peak sun hours and a system derate factor. Free, instant solar sizing.
  • LC Resonant Frequency Calculator
    Calculate the resonant frequency of an LC tank circuit from inductance and capacitance using f = 1/(2π√(LC)). Supports H/mH/µH/nH and F/µF/nF/pF.
  • Speed, Distance & Time Calculator
    Free Speed, Distance & Time calculator. Solve for speed, distance, or time using d = s × t. Supports km, miles, meters, hours, minutes & seconds.
  • Volts, Amps, Watts, Ohms Calculator
    Ohm's law calculator: enter any two of voltage, current, resistance or power and instantly compute the other two using V=IR, P=VI, P=I²R, P=V²/R.
  • Monthly Electricity Bill Estimator
    Estimate your monthly electricity bill from kWh usage, your rate per kWh, and any fixed service charge. See monthly and annual cost instantly.
  • Partially Filled Circle Area Calculator
    Calculate the filled cross-section area and fill percentage of a partially filled circle or cylindrical tank from radius and fill depth.

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