Physics and Engineering

  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Kinetic Friction Incline Acceleration Calculator
    Calculate the acceleration of a block sliding down a rough incline from angle, kinetic friction coefficient, and gravity using a = g(sinθ − μcosθ).
  • Coefficient of Restitution Calculator
    Calculate the coefficient of restitution (e) from collision velocities or from drop and bounce heights. Free, instant physics calculator.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Pump Affinity Laws Calculator
    Use the pump affinity laws to find new flow, head, and power when impeller speed changes. Enter initial values and the new RPM to get instant results.
  • HVAC Compression Ratio Calculator
    Calculate HVAC and refrigeration compressor compression ratio from discharge and suction pressures (gauge or absolute), with altitude adjustment.
  • Weld Metal Weight Calculator
    Calculate deposited weld metal weight for a fillet weld from leg size, length and material density. Metric, with cross-sectional area and volume.
  • Solar Power Calculator
    Estimate the solar PV system size you need and its daily, monthly, and yearly energy output from your usage, peak sun hours, and performance ratio.
  • Air Conditioner Horsepower Calculator
    Calculate the air conditioner horsepower (HP) you need based on room size. Estimates BTU cooling capacity and recommends a standard AC unit size.
  • Radiator BTU Calculator
    Calculate the radiator BTU output needed to heat any room. Enter room dimensions and type to get required BTU/hr and watts instantly.
  • Refrigerant Charge Calculator
    Calculate total HVAC refrigerant charge from factory base charge plus liquid line set length and charge per foot. Results in oz, lb, and grams.
  • Orbital Speed Calculator
    Calculate the orbital speed and period of a satellite from the central body mass and orbital radius using Newton law of gravitation.

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