Physics and Engineering calculators cover applied science and design — material weights, fluid flow, air density, and gas-line sizing. Popular tools include the Metal Weight Calculator, Manning's Pipe Flow Calculator, Air Density Calculator, Pipe Weight Calculator, and Gas Line Calculator.
Enter your parameters below for an instant result, or open the Trending tab to see what engineers are calculating this week. Every calculator is free and works on any device.
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Air Flow Rate Calculator From Pressure and DiameterCalculate air flow rate from pressure difference and pipe diameter. Get volumetric flow in m³/s, m³/h and CFM plus velocity using Bernoulli equation.
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Orbital Speed CalculatorCalculate 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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Refrigerant Charge CalculatorCalculate total HVAC refrigerant charge from factory base charge plus liquid line set length and charge per foot. Results in oz, lb, and grams.
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Home Solar Panel CalculatorEstimate how many solar panels and what system size (kW) you need based on your monthly electricity use, peak sun hours, panel wattage and efficiency.
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Voltage Drop Calculator (mm²)Calculate cable voltage drop in volts and percent for single-phase and three-phase copper or aluminium conductors sized in mm², by current and length.
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HVAC Compression Ratio CalculatorCalculate HVAC and refrigeration compressor compression ratio from discharge and suction pressures (gauge or absolute), with altitude adjustment.
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3 Phase Voltage Drop CalculatorCalculate three-phase voltage drop from load current, cable length, conductor resistivity, cross-section and power factor. Get volts dropped and percentage.
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Weld Metal Weight CalculatorCalculate deposited weld metal weight for a fillet weld from leg size, length and material density. Metric, with cross-sectional area and volume.
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Solar Power CalculatorEstimate the solar PV system size you need and its daily, monthly, and yearly energy output from your usage, peak sun hours, and performance ratio.
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Manning's Pipe Flow CalculatorCompute flow rate (discharge), velocity, area and hydraulic radius in a circular pipe using the Manning equation for full or partially full pipes.
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18650 Battery Pack CalculatorCalculate the voltage, capacity (Ah), total cell count and energy (Wh) of an 18650 battery pack from any series-parallel (SxP) configuration.
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DC Voltage Drop CalculatorCalculate DC voltage drop across wire from current, length, and resistance. Get volts dropped, drop percentage, and voltage at the load instantly.
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Air Conditioner Horsepower CalculatorCalculate the air conditioner horsepower (HP) you need based on room size. Estimates BTU cooling capacity and recommends a standard AC unit size.
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Radiator BTU CalculatorCalculate the radiator BTU output needed to heat any room. Enter room dimensions and type to get required BTU/hr and watts instantly.
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Density, Mass and Volume SolverSolve the density formula ρ = m/V for density, mass or volume. Enter any two values and instantly get the third with this free physics calculator.
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Ohm's Law Solver (V = IR)Solve Ohm's Law (V = IR) for voltage, current, or resistance. Enter any two values to instantly find the third, plus power dissipation.
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Specific Gravity to Density CalculatorConvert specific gravity (SG) to density. Multiply SG by the reference water density (1000 kg/m³) to get density in kg/m³, g/cm³ and g/L instantly.
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Hydropower Output CalculatorCalculate hydroelectric power output from water flow rate, head, and efficiency using P = ρgQHη. Results in watts and kilowatts.
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Kinematic Viscosity CalculatorCalculate kinematic viscosity (ν) from dynamic viscosity (μ) and density (ρ) using ν = μ/ρ. Get results in m²/s, Stokes, and centistokes.
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Density Altitude CalculatorCalculate density altitude from field elevation, altimeter setting, and OAT using DA = PA + 120 x (OAT - ISA). Quick pilot performance estimate.
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Water Density by Temperature CalculatorCalculate the density of water at any temperature from 0 to 100 °C using the standard empirical polynomial. Results in kg/m³ and g/cm³.
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Water Pressure Loss from Elevation CalculatorCalculate water pressure loss from elevation change using 0.433 psi per foot. Enter elevation in feet and specific gravity to get psi, head, and bar.
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GPM to CFS ConverterConvert gallons per minute (GPM) to cubic feet per second (CFS) instantly. Enter a flow rate and get an accurate CFS value using CFS = GPM / 448.831.
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Acre-Feet to Gallons CalculatorConvert acre-feet to US gallons instantly. Enter acre-feet and get the exact gallon volume using 1 acre-foot = 325,851 gallons.
Frequently asked questions
What can I calculate with these physics and engineering tools?
Material and component weights, fluid mechanics such as open-channel and pipe flow, air and gas properties like density, and sizing calculations for lines and systems.
Are the results suitable for engineering work?
They apply standard equations and reference values and are great for estimates and checks. For designs that affect safety or code compliance, verify against the governing standard and have a qualified engineer review them.
Are these calculators free?
Yes — free, no sign-up, and they work on any device.
How do I make sure my units are right?
Check each input's unit label before entering values; mixing unit systems is the most common source of error in engineering calculations.
Which tools are most popular?
This page orders them by usage; the Trending tab shows what's rising this week.
