Browse 45 free calculators in the Physics category.
Momentum Calculator - Mass times velocity, the impulse that changes it, and a one-dimensional collision solved both ways. Kilograms, grams, tons or pounds in; momentum, energy and the force behind the impact out.
Force Calculator - Work out any one of force, mass or acceleration from the other two, or the weight of a mass under four different gravities. Newtons, kilonewtons, kilogram-force and pounds-force, all four on every answer.
Kinetic Energy Calculator - How much energy is a moving body actually carrying? Enter a mass and a speed for the joules, or work back from an energy, and see the fall height that matches it.
Potential Energy Calculator - How much energy does it take to lift something, and how much comes back when it falls? Enter a mass and a height for the answer in joules, kJ, MJ, kWh and kcal, or work backwards to either input.
Work Calculator - Only the part of a force pointing along the movement does any work, and this is how much. Give it a force, a distance and the angle between them for the answer in joules, kJ, MJ, kWh and kcal.
Mechanical Power Calculator - Do the same job four times faster and it needs four times the power, though nothing else about it changes. Give it a work figure and a time for watts, kilowatts, mechanical hp, metric PS and BTU/h.
Torque Calculator - A wheel nut wanting 120 N.m takes 800 N from a short wrench and 120 N from a meter-long bar. Work out the torque, the force or the arm, in metric and imperial at once.
Kinetic Friction Calculator - A 60 kg dresser needs 205.9 N to break loose and 117.7 N to keep moving. Both numbers, for eleven surface pairs, on the flat or on a slope, in newtons and pounds.
Pendulum Period Calculator - A one-meter pendulum takes 2.006 s to swing there and back, and the mass of the bob changes nothing. Add an amplitude and you get the exact period, not the textbook one.
Thermal Expansion Calculator - Steel moves 6 mm per 10 m per 50 K and PVC moves 40 mm. Get the change for fifteen solids and four liquids, in Celsius or Fahrenheit, as a length, an area or a volume.
Specific Heat Calculator - How long does a 1.5 kW kettle need for 1.5 kg of water? 502.32 kJ, so 5.58 minutes. Solve Q = m x c x dT for the heat, the mass, the temperature change or the coefficient.
Thermal Conductivity Calculator - A bare brick wall leaks 1,175 W and the same wall under 15 cm of wool leaks 169. Get the heat flow, the R-value in both unit systems and what one more layer would buy.
Hooke's Law Calculator - How stiff is a spring that a 2 kg weight pulls down 4 cm? 490.3 N/m, or 2.8 lbf/in. Solve F = kx for the force, the spring constant or the stretch, and see the energy it stores.
Simple Harmonic Motion Calculator - Position, velocity and acceleration of an oscillator at any moment, from its amplitude and its period or frequency. Add a mass for joules, the equivalent spring constant and peak force.
Buoyancy Calculator - Find out whether it floats, how deep it sits and how much more it can carry, or what it weighs under water. Archimedes' principle across nine fluids, in liters, gallons or cubic feet.
Acceleration Formula Calculator - How hard was that pull, in numbers? Enter three of the four quantities of straight-line motion and read the fourth, with the rate in m/s2, ft/s2 and g, and the distance alongside it.
Density Calculator - Weigh it, measure it, find out what it is. Density, mass or volume from the other two, with specific gravity, a float or sink verdict and your figure placed on a ladder of 27 materials.
Temperature Converter - One reading in, all four scales out: Fahrenheit, Celsius, Kelvin and Rankine, with the formula written out and a note on what that temperature means in practice.
Thermal Efficiency Calculator - How much of the fuel you pay for becomes heat or work? Enter energy in and out in kWh, BTU or therms and get the efficiency, the losses in dollars and a check against typical furnaces.
Gravitational Force Calculator - Work out the pull between any two masses with Newton's law of gravitation, in newtons and pounds-force, or see how strong surface gravity is on eleven bodies from Pluto to the Sun.
Snell's Law Calculator - Refraction angle, critical angle and the share of light reflected at a surface, from air into water to diamond into air, with Snell's law written out for your own numbers.
Refractive Index Calculator - Glass, acrylic or quartz? Turn two measured angles, a speed of light or a refractometer reading into an index and see which of 18 reference materials it fits.
Thin Lens Calculator - Image distance, object distance or focal length from the thin lens equation, in mm, cm or inches, with magnification, lens power in diopters and whether the image is real.
Magnifying Glass Calculator - A +10 diopter lens magnifies 2.5x or 3.5x depending on how you hold it. Enter the power, the focal length or the X on the label to see where to keep the page and how large fine print looks.
Wavelength to Color Calculator - What color is 589 nm, and how many terahertz is that? Type a wavelength, frequency or photon energy to get the other two, the band from gamma rays to radio and the color name when light is visible.
Wave Frequency Calculator - How long is a 440 Hz sound wave? 77.95 cm in air, 3.37 m in water. Find frequency, wavelength or wave speed from the other two, with the period, angular frequency and nearest piano key.
Photon Energy Calculator - Photon energy in eV, joules and kJ/mol from nm, Hz or kJ/mol, plus momentum. Add a power in watts to count photons per second, or pick a metal to see if the light frees electrons.
Speed of Sound Calculator - Find the speed of sound in air at any temperature, in water, steel and 14 other materials, then turn a lightning-to-thunder delay into miles or a distance into seconds.
Echo Distance Calculator - Distance to a cliff, a lake bottom or the far side of a steel plate from a round-trip echo time, with the seawater speed set by temperature and salinity and times down to microseconds.
Ohm's Law Calculator - Know two of volts, amps and ohms? Get the third plus the power in watts, or size an LED series resistor and see the next E12 and E24 values with the current each one gives.
Electrical Power Calculator - Watts from volts and amps, amps and ohms, or volts and ohms, with the power factor for single- and three-phase AC, plus optional kWh and cost per day, month and year.
Amps Calculator - Convert watts to amps for DC, single-phase or three-phase AC, or find amps from volts and ohms, then see the smallest standard breaker and copper wire gauge for the load.
Parallel Plate Capacitor Calculator - How much capacitance do two plates give? Enter the area, the gap and the dielectric to get pF or nF, stacked layers, charge and energy, and the same plates with 11 other dielectrics.
Capacitor Energy Calculator - How many joules does a capacitor hold? Get energy, charge and Wh from capacitance and voltage, solve for µF or volts, and see how long a resistor takes to drain it.
Transformer Calculator - Find the secondary voltage, turns or turns ratio of a transformer, then the full-load amps on both sides from its VA or kVA rating, for single-phase or three-phase supplies.
Battery Life Calculator - Runtime of any battery in hours, days or years, from mAh, Ah or Wh and a load in mA, A or W, with depth of discharge and inverter losses when you need them.
Battery Charging Time Calculator - How long until full? Charging time for phones, power banks, cells and 12 V batteries from mAh, Ah or Wh and the charger in amps or watts, between any two charge levels.
Power Bank Capacity Calculator - Real phone charges from any power bank, counted in watt-hours instead of label mAh, with the losses from 3.7 V cells to 5 V USB and the FAA limit for flying.
Inductance Calculator - Find the inductance of an air-core coil, a toroid or any core with an AL value, or the turns to wind for a target, using Wheeler's formula instead of the ideal solenoid.
RLC Circuit Calculator - Which capacitor turns a 10 mH coil into a 1 kHz filter? Enter R, L and C for the resonant frequency, Q and bandwidth, or name a target frequency and get the part to buy.
Magnetic Force Calculator - Work out the magnetic force on a current-carrying wire, on a moving electron or proton, or between two parallel wires, with the radius and period of a charged particle path.
Electric Motor Efficiency Calculator - Measure what a motor really returns at the shaft: efficiency from volts, amps and power factor, the losses in watts, and the energy and money they cost over the hours it runs.
Voltage Drop Calculator - Voltage drop over a long run, turned into a wire gauge: copper or aluminum, AWG to 500 kcmil, 120 to 480 V or DC, with the volts left at the load and the longest run each size allows.
Doppler Effect Calculator - Why does a siren drop in pitch as it passes? Work out the frequency heard for sound, a radar reflection or light, or turn a measured shift back into a speed, in mph, km/h or m/s.
Punch Force Calculator - Estimate the peak force of a punch in newtons and pounds-force from hand speed, the mass behind the fist and contact time, checked against punches measured on Olympic boxers.