Science & Engineering
Physics and electronics calculators: Ohm's law, resistor color codes, density, speed and distance, energy and more, with the formulas shown.
555 Timer Calculator
Calculate 555 timer astable frequency, period, high and low times and duty cycle from R1, R2 and the timing capacitor. Free oscillator design helper.
Battery Life Calculator
Estimate how long a device runs on a battery from its capacity in mAh and current draw in mA. Includes a real-world efficiency factor for an honest figure.
Bernoulli Equation Calculator
Solve Bernoulli's equation for the downstream pressure from density, upstream pressure, two velocities and two elevations for steady incompressible flow.
Capacitive Reactance Calculator
Calculate the capacitive reactance Xc of a capacitor at any frequency with Xc = 1 / (2 pi f C). Enter frequency and capacitance to get ohms instantly.
Capacitor Code Calculator
Decode capacitor codes like 104 or 223 into pF, nF and uF instantly. Reads 2-digit and 3-digit codes plus tolerance letters. Free electronics tool.
Codon Translator
Translate an mRNA or DNA sequence into amino acids. Read codons in triplets, get the protein in one and three letter codes, and find the stop codon.
Coulomb's Law Calculator
Calculate the electrostatic force between two point charges with Coulomb's law, F = k q1 q2 / r squared. Shows attract or repel. Free physics calculator.
Darcy-Weisbach Calculator
Calculate pipe friction head loss and pressure drop with the Darcy-Weisbach equation from friction factor, length, diameter, velocity and fluid density.
Decibel Calculator
Add sound levels in decibels and convert between ratios and dB. Combine noise sources logarithmically and switch between power and amplitude ratios.
Density Calculator
Calculate density, mass or volume from the other two using density = mass / volume. Supports grams, kilograms, cubic centimetres, litres and more.
Dilution Calculator
Solve the dilution equation C1V1 = C2V2 for any one unknown. Find the stock volume to pipette or the final concentration for any solution dilution.
DNA to mRNA Converter
Transcribe a DNA sequence into mRNA online. Pick the coding or template strand, get the base for base RNA result, and view the complementary DNA strand.
Efficiency Calculator
Calculate energy or work efficiency as output divided by input times 100. Enter any two values to find the third plus the energy lost. Free physics tool.
Empirical Formula Calculator
Find the empirical formula from percent composition or masses. Enter each element percent, like 40% C and 6.7% H, to get the lowest whole number ratio.
Escape Velocity Calculator
Calculate escape velocity from any planet, moon or star with v = sqrt(2GM/r). Pick Earth, Mars or Jupiter presets or enter mass and radius. Free tool.
Flow Rate Calculator
Calculate volumetric flow rate through a round pipe from diameter and velocity, or find velocity from flow rate. Results in m3/s, L/min and GPM.
Force Calculator
Solve Newton's second law online. Enter any two of force, mass or acceleration and get the third, in newtons, kilograms and metres per second squared.
Gravitational Force Calculator
Calculate the gravitational force between two masses with Newton's law of universal gravitation, F = G m1 m2 / r squared. Free physics calculator.
Half-Life Calculator
Solve radioactive decay with N = N0 times one half raised to t over T. Enter any three of initial, remaining, half-life and time to find the fourth.
Hydraulic Radius Calculator
Calculate hydraulic radius, flow area and wetted perimeter for full pipes, open rectangular channels and full rectangular ducts. SI units, instant results.
Ideal Gas Law Calculator
Solve the ideal gas law PV = nRT for pressure, volume, moles or temperature. Enter any three values, pick your units in atm, kPa, L, m3, K or C.
Inductive Reactance Calculator
Calculate the inductive reactance Xl of an inductor at any frequency with Xl = 2 pi f L. Enter frequency and inductance to get the reactance in ohms.
Kinetic Energy Calculator
Calculate kinetic energy, mass or velocity using KE = 1/2 m v^2. Enter any two values in SI units (kg, m/s, joules) to solve for the third.
LED Resistor Calculator
Calculate the series resistor an LED needs. Enter supply voltage, LED forward voltage and current to get the resistance, nearest E12 value and power.
Lens Magnification Calculator
Solve the thin lens equation 1/f = 1/do + 1/di and find magnification m = -di/do. Enter any two of focal length, object and image distance. Free tool.
Light Year Converter
Convert astronomical distances between light-years, AU, parsecs, kilometres, miles and metres. Fast, accurate unit conversion with worked examples. Free.
Molar Mass Calculator
Calculate the molar mass and molecular weight of any chemical formula. Get a full per element breakdown for compounds like H2O, NaCl, H2SO4 and hydrates.
Molarity Calculator
Calculate molarity in mol per litre and solve for moles, volume or concentration. Find moles from mass and molar mass, then get the missing value.
Mole Calculator
Convert between moles, mass and particles. Enter mass and molar mass, or moles, or a particle count, and get the rest using Avogadro's number.
Ohm's Law Calculator
Solve Ohm's law online. Enter any two of voltage, current, resistance or power and get the other two, with the V, I, R and P formulas shown.
Op-Amp Gain Calculator
Calculate op-amp voltage gain and gain in dB for inverting and non-inverting configurations from the input and feedback resistors. Free EE design tool.
Orbital Period Calculator
Calculate orbital period from Kepler's third law, T = 2 pi sqrt(a cubed / GM). Enter the semi-major axis and central mass to get seconds, days and years.
Percent Composition Calculator
Calculate the percent composition by mass of each element in a chemical formula. Enter a compound like H2O or CO2 and get the molar mass breakdown.
Percent Yield Calculator
Calculate percent yield from actual and theoretical yield. Solve for actual or theoretical yield too, with a flag when the result exceeds 100 percent.
pH Calculator
Calculate pH, pOH and the H+ and OH- concentrations at 25C. Enter any one value and get the other three, with an acidic, neutral or basic verdict.
Planet Weight Calculator
Find your weight on other planets and the Moon. Enter your Earth weight in pounds or kilograms to see it scaled by each body surface gravity.
Power Calculator
Calculate power online. Solve mechanical power from work and time (P = W / t) or electrical power from voltage and current (P = V x I), in watts.
Pressure Calculator
Solve pressure from force and area online. Enter any two of force, area or pressure and get the third, with newtons, pounds, square metres, psi and more.
Projectile Motion Calculator
Calculate projectile range, max height and time of flight from launch speed and angle. Supports custom gravity and launch height. Free physics calculator.
Pump Power Calculator
Calculate pump hydraulic power and shaft power from flow rate, head, fluid density and efficiency. Results shown in both watts and kilowatts.
Punnett Square Calculator
Build a monohybrid Punnett square from two parent genotypes. See the 2x2 cross grid, genotype ratios like 1:2:1 and the dominant to recessive split.
RC Time Constant Calculator
Find the RC time constant from resistance and capacitance, plus charge times and the cutoff frequency. Enter any two of R, C and tau to solve the third.
Resistor Calculator
Add resistors in series or parallel and get the total resistance in ohms. Enter any number of values and the calculator shows the result with the formula.
Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes to ohms and tolerance, or encode a resistance into color bands. Free, with the values formatted clearly.
Resonant Frequency Calculator
Find the resonant frequency of an LC circuit with f = 1 / (2 pi sqrt(L C)). Enter inductance and capacitance to get the frequency and angular frequency.
Reynolds Number Calculator
Calculate the Reynolds number for pipe flow from velocity, diameter and viscosity, then see whether the flow is laminar, transitional or turbulent.
Snell's Law Calculator
Calculate the angle of refraction with Snell's law, n1 sin t1 = n2 sin t2. Find the refracted angle, the critical angle and total internal reflection. Free.
Specific Heat Calculator
Solve Q = m c deltaT for heat, mass, specific heat or temperature change. Enter any three SI values to get the fourth, with common material hints.
Speed Distance Time Calculator
Work out speed, distance or time from the other two with speed = distance / time. Supports m/s, km/h and mph, plus metres, kilometres and miles.
Telescope Magnification Calculator
Calculate telescope magnification from focal lengths, plus max useful power, exit pupil and focal ratio from your aperture. Free astronomy optics tool.
Torque Calculator
Calculate torque from force, lever arm and angle using T = F x r x sin(theta). Solve for torque, force or lever arm in newton-metres, 90 degrees by default.
Voltage Divider Calculator
Calculate the output of a resistive voltage divider. Enter the input voltage and two resistors to get Vout, the current and the divider ratio instantly.
Voltage Drop Calculator
Calculate DC voltage drop along a wire run from current and resistance, or from resistance per meter and length. See volts dropped, percent and end voltage.
Wavelength Frequency Calculator
Convert wavelength to frequency and back using c = f x lambda. Enter a wavelength or frequency in metres, nm, Hz, MHz or GHz and get the photon energy too.
Wire Gauge Calculator
Convert an AWG wire gauge to diameter, cross-sectional area and copper resistance per km. Higher gauge means thinner wire. Free electronics calculator.