Science Tools
Free science and engineering calculators — Ohm's law, resistor colour codes, molecular weight, pH, kinetic energy, half-life and significant figures. All run in your browser.
All Science tools
Ohm's Law Calculator
Solve for voltage, current, resistance or power — any one from the others.
Voltage Divider Calculator
Work out the output of a two-resistor divider, or the resistors for a target output.
LED Resistor Calculator
Find the current-limiting resistor for an LED, with the nearest standard value.
Resistor Color Code Calculator
Decode 4, 5 and 6-band resistors — or go the other way from a value to its bands.
Capacitor Calculator
RC time constant, capacitive reactance, stored energy and series/parallel totals.
Frequency Calculator
Convert between frequency, period and wavelength for any wave speed.
Force Calculator
Solve F = ma for force, mass or acceleration, with weight on Earth shown.
Kinetic Energy Calculator
Solve KE = ½mv² for energy, mass or velocity, with everyday comparisons.
Density Calculator
Solve ρ = m/V for density, mass or volume, with common materials for comparison.
Pressure Converter
Convert pascals, bar, psi, atmospheres, torr and mmHg — with everyday references.
Molecular Weight Calculator
Parse a chemical formula and get its molar mass, with each element's contribution.
Stoichiometry Calculator
Balance the books on a reaction — limiting reagent, theoretical yield and leftovers.
pH Calculator
Convert between pH, pOH and ion concentration, with a visual scale.
Half Life Calculator
Work out remaining quantity, elapsed time or half-life for exponential decay.
Significant Figures Calculator
Count significant figures and round to any precision, with the rules explained.