Science & Engineering

From dry bulb plus relative humidity, wet bulb, dew point or humidity ratio, get every moist-air property: enthalpy, specific volume, density and more.

Science & Engineering

Decode 4/5/6-band axial resistors into ohm value with tolerance — interactive color picker, gold/silver multipliers and tolerances supported.

Science & Engineering

Find the nearest standard resistor in E3 to E192 for any value, and the best pair of standard resistors in series or parallel to hit it more closely.

Science & Engineering

Decode 3-digit ceramic capacitor codes (104, 473K, 4R7) into picofarads, nanofarads and microfarads, with the tolerance-letter lookup.

Science & Engineering

Solve V, I, R, P from any two known values. V=IR, P=VI, P=V²/R, P=I²R — pick which pair you have, get the other two instantly.

Science & Engineering

Compute the output voltage of a two-resistor divider, or find the R2 you need for a target output, plus current and power dissipation.

Science & Engineering

Voltage drop, load voltage and power lost in a copper or aluminium cable, DC, single- or three-phase, plus the smallest AWG or mm² size within your limit.

Science & Engineering

PCB trace width for a current and temperature rise, or the current a trace can carry, per IPC-2221 — with resistance, voltage drop and power loss.

Science & Engineering

Characteristic impedance of a PCB microstrip or stripline from its geometry, or the trace width for 50 Ω, with effective εr, delay and L and C per length.

Science & Engineering

Find capacitive reactance (Xc), inductive reactance (XL), or the LC resonant frequency, with pF–F, nH–H and Hz–GHz unit pickers.

Science & Engineering

Frequency, period, high and low time and duty cycle of a 555 astable, the pulse width of a monostable, or RA and RB for a target frequency with E24 values.

Science & Engineering

Time constant, cutoff frequency, step response and low- or high-pass gain and phase of an RC or RL circuit, plus the time to reach a voltage.

Science & Engineering

Resonant frequency of an LC circuit, or the L or C for a target frequency, with reactance and impedance; add R for Q, bandwidth and −3 dB points.

Science & Engineering

Inductance of a single-layer air-core coil from diameter, length and turns using Nagaoka's exact coefficient, or the turns needed for a target inductance.

Science & Engineering

Gain, dB, output voltage, input impedance and bandwidth of inverting, non-inverting and difference op-amp stages, or standard resistors for a target gain.

Science & Engineering

How long a battery lasts on a constant or duty-cycled load, with usable-capacity derating and Peukert's law, or the capacity a target runtime needs.

Science & Engineering

Junction, case and heat-sink temperatures from power and thermal resistances, the heat sink a part needs or the power it can shed, with regulator loss.

Science & Engineering

Size the current-limiting resistor for an LED or series string from supply voltage, forward voltage and current — with the nearest E24 value.

Science & Engineering

Convert between mass, moles, volume and molar concentration of a solution — solve for molarity, the mass to weigh out, or the volume to make up.

Science & Engineering

Calculate the molar mass and percent composition of any chemical formula, with parentheses and hydrates, in your browser.

Science & Engineering

Apply C₁V₁ = C₂V₂ to find any unknown — the stock volume to take, the final volume, or either concentration — plus the amount of solvent to add.

Science & Engineering

Convert between pH, pOH, [H⁺] and [OH⁻] at 25 °C — enter any one and get the other three, plus an acidic / neutral / basic verdict.

Science & Engineering

Solve PV = nRT for pressure, volume, moles or temperature, with Pa/kPa/bar/atm/mmHg/psi, mL/L/m³, mol/mmol and K/°C/°F units.

Science & Engineering

Calculate the frequency an observer hears when source or observer moves — set emitted frequency, wave speed and each velocity to get the shift.

Science & Engineering

ISA / U.S. Standard Atmosphere 1976 temperature, pressure, density, speed of sound and viscosity from −5 to 80 km, plus pressure and density altitude.

Science & Engineering

Period, speeds, escape velocity and energy of an orbit around Earth, the Moon, Mars or any body, plus Hohmann transfer Δv and time between two orbits.

Science & Engineering

Δv of a multi-stage rocket from propellant, dry mass and specific impulse, with burn times and thrust-to-weight, or the propellant a target Δv needs.

Science & Engineering

Distance, bearings and midpoint between two lat/lon points on the WGS 84 ellipsoid, or the destination from a start point, bearing and distance.

Science & Engineering

Magnetic declination, inclination and field strength for any place, altitude and date from 2025 to 2030, with true/magnetic bearing conversion.

Science & Engineering

Find the sun's elevation and azimuth for any place and time from 1900 to 2100, with shadow length and direction, air mass and an hour-by-hour table.

Science & Engineering

Convert between decibels and linear ratios for voltage/SPL (20·log) or power (10·log), sum dB SPL sources, and look up dBV, dBu, dBm and dBFS.

Science & Engineering