Physics and Engineering

  • 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.
  • Electricity Carbon Footprint Calculator
    Calculate the CO₂ carbon footprint of your electricity use from kWh and your grid emission factor (kg CO₂/kWh), per period and total.
  • Three-Phase Power Calculator
    Calculate three-phase active, apparent and reactive power from line voltage, line current and power factor using P = √3·V·I·cos φ.
  • Weight Calculator (W = m·g)
    Calculate weight as a force in newtons from mass and gravitational acceleration using W = m·g. Free, instant, and works for any planet's gravity.
  • Magnification Calculator
    Calculate optical magnification of a lens or mirror from object and image distances using M = -di/do. Shows magnitude, orientation, and image type.
  • Sound Intensity Level Calculator
    Calculate sound intensity level in decibels (dB) from sound intensity using L = 10·log10(I/I0) with the standard reference 1e-12 W/m².
  • Critical Angle Calculator
    Calculate the critical angle for total internal reflection from two refractive indices using θc = arcsin(n₂/n₁). Free, fast and accurate.
  • Rectangular Pool Volume Calculator
    Calculate how many gallons of water your rectangular pool holds. Enter length, width, and average depth in feet to get the volume instantly.
  • Rectangle Area Moment of Inertia Calculator
    Calculate the area moment of inertia (Ix and Iy) of a rectangular cross-section about its centroidal axes from width and height.
  • Specific Heat Capacity Calculator
    Calculate specific heat capacity from heat energy, mass and temperature change using c = Q / (m·ΔT). Fast, accurate physics tool with worked example.
  • Final Temperature of Mixing Two Liquids Calculator
    Calculate the final equilibrium temperature when two liquids (such as water) of different masses, specific heats, and temperatures are mixed together.
  • VinFast Monthly Charging Budget Calculator
    Estimate your VinFast EV's monthly home-charging cost from miles driven, efficiency (mi/kWh), and your electricity rate. Includes yearly and per-mile costs.
  • Heat Transfer Rate Calculator
    Calculate heat energy transferred (Q = mcΔT) from mass, specific heat, and temperature change. Free physics calculator with joules and kilojoules output.
  • VinFast VF3 Charging Cost Calculator
    Estimate the cost to charge a VinFast VF3 EV from your start to target state of charge using battery size, charging efficiency, and your electricity rate.
  • Lighting kWh Usage Calculator
    Calculate the kWh energy used by your lighting and its cost. Enter bulbs, watts, hours per day and days to estimate consumption and electricity bills.
  • AC Power Calculator
    Calculate real (W), reactive (VAR) and apparent (VA) power in single-phase AC circuits from voltage, current and power factor. Free online tool.
  • Maximum Lights per Circuit Calculator
    Find how many light fixtures you can safely put on a circuit. Enter voltage, breaker amps and watts per fixture to get the max count at the 80% rule.
  • Lighting Watts to Amps Calculator
    Convert lighting watts to amps instantly. Enter total fixture wattage, voltage, and power factor to find the current draw for sizing circuits and breakers.

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