Science & Engineering

Estimate battery runtime from capacity (mAh) and current draw (mA). Add an efficiency factor (%) and optionally include self-discharge rate for accurate projections.

Calculate the BTU cooling capacity needed for a room based on dimensions, insulation, sun exposure, and occupancy.

Decode 3-digit ceramic capacitor codes (like 104 = 100 nF) to picofarads, nanofarads, and microfarads. Also convert a capacitance value back to its 3-digit code.

Estimate your personal annual CO₂e emissions from transport, home energy, diet, and shopping. See a breakdown by category and get personalised reduction tips.

Convert between decibels and voltage or power ratios. Calculate sound pressure level (dB SPL) from pressure in Pascals. Convert dB to amplitude ratios and back.

Calculate density, mass, or volume using D = m/V. Supports metric and imperial units. Shows the triangle relationship and common material densities for reference.

Calculate the observed frequency of a moving sound source using the Doppler effect formula. Enter source frequency, velocities, and wave speed to compute the perceived frequency and pitch shift in semitones.

Calculate free-fall distance, velocity, or time using h=½gt² and v=gt. Supports metric (m/s²) and imperial (ft/s²). Ignores air resistance.

Calculate remaining quantity, elapsed time, or half-life for radioactive decay using N(t)=N₀×(½)^(t/t½). Supports any initial quantity and time unit.

Solve Hooke's Law F = kx for force, spring constant, or extension. Also calculates elastic potential energy stored in the spring (U = 1/2kx^2).

Solve PV=nRT for any unknown variable. Supports atm, Pa, kPa, bar for pressure; L, mL for volume; K and °C for temperature. Shows step-by-step working.

Browse all 118 elements with atomic number, symbol, mass, category, period, and group. Search by name, symbol, or number.

Calculate kinetic energy (KE = 1/2mv^2) and gravitational potential energy (PE = mgh). Solve for any of mass, velocity, or height.

Calculate the correct series resistor for your LED circuit. Enter supply voltage, forward voltage, and forward current; get resistance in ohms and nearest E12 value.

Solve the thin lens equation for focal length, object distance, or image distance. Computes magnification and tells you whether the image is real or virtual, upright or inverted.

Simulate AND, OR, NOT, NAND, NOR, XOR, XNOR, and BUFFER logic gates interactively.

Enter a chemical formula (e.g. H₂O, NaCl, C₆H₁₂O₆) and instantly calculate molar mass with a per-element breakdown. Supports parentheses and nested groups.

Calculate solution molarity (moles per liter), dilute solutions using C₁V₁=C₂V₂, and convert between grams, moles, and liters. All offline.

Calculate NE555 timer frequency, period, duty cycle, and pulse width for both astable (oscillator) and monostable (one-shot) configurations. Enter R1, R2, and capacitor values.

Calculate op-amp gain for inverting, non-inverting, and difference amplifier configurations. Enter Rf and Rin to get the gain, or supply input voltage to compute the output.

Calculate the period (T = 2pisqrt(L/g)), frequency, and length of a simple pendulum. Enter any two values to solve for the third. Supports custom gravitational acceleration.

Convert between pH, hydrogen ion concentration [H], and pOH. Determine whether a solution is acidic, neutral, or basic.

Look up 20+ fundamental physics constants including speed of light, Planck constant, gravitational constant, and more.

Calculate swimming pool volume in gallons or litres and the chlorine dose needed to reach a target ppm for rectangular, oval, or round pools.

Calculate projectile range, maximum height, time of flight, and velocity components from initial speed and launch angle. Supports m/s and ft/s.

Calculate the Reynolds number (Re = vL/) for any fluid and pipe geometry. Instantly determine whether flow is laminar, transitional, or turbulent.

Solve Snell's Law nsin(theta) = nsin(theta) for the refracted angle or refractive index. Automatically detects total internal reflection and shows the critical angle.

Solve the specific heat equation Q = m x c x T for any of the four variables: heat energy (Q), mass (m), specific heat capacity (c), or temperature change (T). Includes a table of common materials.

Solve the voltage divider formula V_out = V_in × R2/(R1+R2) for any unknown. Shows current draw and supports standard E12/E24 resistor series lookup.

Convert between wavelength and frequency for light, radio waves, and sound. Uses c=λf for EM waves and v=λf for sound with a customizable wave speed.

Look up AWG wire gauge properties: diameter (mm/in), cross-section area, resistance per 100 ft/m, and maximum current capacity for chassis and in-wall wiring.