Science calculators
Physics, chemistry and electrical calculators with the formula shown: energy, motion, density, molarity, gas laws, half-life, Ohm's law, power and voltage drop.
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Physics
Force, energy, motion, density, sound and waves.
Kinetic Energy CalculatorKinetic energy, mass or speed from KE = ½mv² in mixed units (J, kJ, kWh, kcal, ft·lbf, BTU; km/h, mph, knots), plus momentum, potential energy, drop height and impact speed, rough braking distance and relativistic energy near light speed.Open calculator Projectile Motion CalculatorRange, maximum height, time of flight and impact speed and angle from launch speed, angle and height, with a trajectory plot, the angles or speed to hit a target, position at any time, higher or lower landing ground, Moon and Mars gravity and a range-by-angle table. No air resistance.Open calculator Force CalculatorForce, mass or acceleration from Newton's second law F = ma in mixed units (N, kN, lbf, kgf, dyn; kg, lb, oz; m/s², ft/s², g), plus weight on Earth, the Moon, Mars and Jupiter, friction, forces on a slope, acceleration from a change in speed and the net force from several pushes and pulls.Open calculator Density CalculatorDensity, mass or volume from the other two in mixed metric and US units, volume from a cube, box, cylinder or sphere or from water rise, material presets, specific gravity and will it float.Open calculator Decibel CalculatorAdd or subtract sound levels in dB, energy average, power and voltage ratios to dB and back, dBm, dBW, dBV and dBu, pascals to dB SPL, and how a level drops with distance from a point or line source.Open calculator Wavelength CalculatorWavelength, frequency or wave speed from v = f × λ for light, radio or sound (in air at any temperature, water, steel), in Hz to EHz and pm to km or ft and in, plus period, photon energy in eV, wavenumber, the spectrum band and colour, antenna lengths and the nearest musical note.Open calculator
Chemistry
Concentrations, pH, gas laws and radioactive decay.
Molarity CalculatorMass, molar mass, volume or molarity from the other three in mixed units, molar mass from a formula, common compounds, dilution C1V1 = C2V2, % w/v and ppm.Open calculator pH CalculatorpH, pOH, [H⁺] and [OH⁻] from any one in mol/L, mmol/L or µmol/L, with acidic, neutral or basic on a colour scale, plus strong and weak acids and bases (Ka, pKa, Kb, pKb), buffers by Henderson–Hasselbalch, dilution, mixing an acid with a base and pKw at 0–100 °C.Open calculator Ideal Gas Law CalculatorPressure, volume, moles or temperature from PV = nRT in mixed units, from grams too, combined gas law (Boyle, Charles, Gay-Lussac, Avogadro), gas density, molar mass and STP.Open calculator Half-Life CalculatorAmount left, starting amount, time or half-life from the other three, in mixed time units, with the decay constant, mean lifetime, a decay table and curve, and textbook isotopes.Open calculator
Electrical
Ohm's law, power, wiring, batteries and generators.
Ohm's Law CalculatorAny two of voltage, current, resistance and power give the other two, with the formula used on the Ohm's law wheel, series and parallel resistors, LED resistor, voltage divider and AC power.Open calculator kVA, kW and Amps ConverterConvert between kVA, kW, amps and horsepower for single phase, three phase and DC: power factor, kVAR, VA, BTU/h, motor input from shaft horsepower and a table of amps for common kVA sizes.Open calculator Voltage drop calculatorVoltage drop and wire size for DC, single and three phase: volts and % lost, voltage at the load, power lost as heat, copper or aluminium in mm² or AWG, conductor temperature, power factor and the smallest size that stays under your % limit.Open calculator Wire Gauge CalculatorAWG to mm² and back: diameter in mm, inches and mils, cross-section in mm², circular mils and kcmil, nearest metric and AWG size, stranded wire, copper and aluminium resistance per km or 1000 ft at any temperature, weight and a full 4/0 to 40 AWG table.Open calculator Resistor Color Code CalculatorResistor colour bands to ohms and back for 3, 4, 5 and 6 bands: tolerance range, temperature coefficient, nearest E-series value, SMD codes and series/parallel.Open calculator Series and Parallel Resistor CalculatorTotal of 2–10 resistors in series or parallel, each in its own unit, with the formula worked out: capacitors and inductors, the resistor to add for a target, current, voltage and power in each with a rating check, voltage divider and nearest E12/E24 value.Open calculator Generator size calculatorThe generator size in kW and kVA for home or business backup: appliances with running and starting watts, the surge peak, safety margin, power factor, amps on single or three phase, fuel use, runtime on a tank and inverter battery size.Open calculator Battery Life CalculatorHow long a battery lasts: mAh ÷ mA or Wh ÷ W, with usable %, inverter efficiency, sleep/duty cycle, cells in series and parallel, Peukert for lead-acid, charging time and power-bank charges.Open calculator
About the Science calculators
Physics calculators work out kinetic energy and momentum, projectile motion and density, in any mix of metric and US units. Chemistry tools find molarity and dilutions, solve the ideal gas law and work out radioactive half-life.
Electrical tools cover Ohm's law, converting kVA, kW and amps, resistor colour codes, battery life, generator sizing and voltage drop with the wire size you need.
Each page shows the formula and works through your own numbers step by step. For real electrical installations, have the sizes checked by a qualified electrician.