Circuit, capacitor, resistor, magnetic field, and electromagnetic wave calculators. Browse our free electromagnetism tools below — all calculators are instant, accurate, and require no sign-up.
100 Amp Wire Size Calculator — Calculate the correct wire gauge for 100-amp circuits. NEC ampacity tables for copper and aluminum conductors with voltage drop analysis.
220V Wire Size Calculator — Calculate wire gauge for 220/240V circuits. Size conductors for appliances, HVAC, EV chargers, and welders with NEC ampacity tables.
12V Wire Size Calculator — Calculate correct wire gauge for 12V DC systems. Automotive, solar, marine, and LED applications with voltage drop analysis.
3-Phase Motor Amperage Calculator — Calculate 3-phase motor full-load amps from HP, voltage, efficiency, and power factor. NEC Table 430.250 lookup and breaker sizing.
24V Wire Size Calculator — Calculate wire gauge for 24V systems. HVAC thermostats, landscape lighting, sprinkler valves, and access control with voltage drop limits.
AC Wattage Calculator — Calculate AC power: real watts, reactive VAR, and apparent VA from voltage, current, and power factor. Single and 3-phase with cost estimation.
Acoustic Impedance Calculator — Calculate acoustic impedance Z = ρv, reflection and transmission coefficients at material boundaries. Includes material database for ultrasound.
Amp to Wire Size Calculator — Convert amperage to wire gauge using NEC ampacity tables. Copper and aluminum, temperature ratings, conduit fill, and ambient temperature derating.
Beat Frequency Calculator — Calculate beat frequency from two interfering waves. Visualize amplitude modulation, cents difference, and musical interval analysis.
Capacitance Calculator — Calculate capacitance for parallel plate, cylindrical, and spherical capacitors. Dielectric materials, stored charge, energy, and electric field.
Capacitive Reactance Calculator — Calculate capacitive reactance Xc = 1/(2πfC), impedance, phase angle, and cutoff frequency. Frequency response and standard capacitor tables.
Capacitor Calculator — Calculate capacitor charge, energy, time constant, reactance, and series/parallel combinations. RC discharge curve and standard value reference.
Capacitor Charge Time Calculator — Calculate how long a capacitor takes to charge or discharge through a resistor to a target voltage. RC time constant, milestones, and curve.
Capacitor Size Calculator — Calculate the right capacitor size for power factor correction, motor start/run, DC filtering, and audio crossover applications.
Capacitors in Series Calculator — Calculate equivalent capacitance, voltage distribution, and energy for capacitors in series. Visual voltage distribution and per-capacitor breakdown.
Coefficient of Discharge Calculator — Calculate coefficient of discharge (Cd), theoretical and actual flow rates for orifices, nozzles, weirs, and Venturi meters.
Compton Wavelength Calculator — Calculate the Compton wavelength λ_C = h/(mc) for any particle. Explore Compton scattering angles, rest energies, and quantum length scales.
Conductivity to Resistivity Calculator — Convert between electrical conductivity (σ) and resistivity (ρ). Material database, temperature correction, %IACS, and wire resistance.
Critical Damping Calculator — Calculate critical damping coefficient, damping ratio, natural frequency, quality factor, and transient response for second-order systems.
Current Divider Calculator — Calculate branch currents in parallel resistor networks using the current divider rule. Supports any number of resistors with power analysis.
Cyclotron Frequency Calculator — Calculate cyclotron (gyro) frequency, Larmor radius, and relativistic corrections for charged particles in magnetic fields.
Cutoff Frequency Calculator — Calculate cutoff frequency for RC, RL, and RLC filters. Solve for any component value. Frequency response table and filter design.
DC Wire Size Calculator — Calculate correct wire gauge for DC systems with voltage drop limits. Solar, battery, automotive, marine, and LED wire sizing.
Damping Ratio Calculator — Calculate damping ratio (ζ) from system parameters, peak amplitudes, or RLC values. Quality factor, settling time, and response analysis.
De Broglie Wavelength Calculator — Calculate the de Broglie wavelength λ = h/p for any particle. Relativistic support, multiple input modes, energy scans, and scale comparisons.
Electric Field of a Point Charge Calculator — Calculate electric field E = kQ/r² for single or multiple point charges. Includes superposition, dielectric media, and field vs distance tables.
Frequency Bandwidth Calculator — Calculate bandwidth, Q factor, and cutoff frequencies for resonant circuits and filters. Frequency response table, RLC values, and selectivity analysis.
Faraday's Law EMF Calculator — Calculate induced EMF using Faraday's law of electromagnetic induction: ε = −NdΦ/dt. Supports flux, field, and motional EMF modes.
Frequency of Light Calculator — Calculate light frequency from wavelength using f = c/λ. Visible spectrum color mapping, photon energy in eV, wave number, and electromagnetic spectrum reference table.
Frequency to Wavelength Calculator — Convert frequency to wavelength for light, sound, and radio waves using λ = v/f. Supports EM waves, sound in air with temperature correction, and custom media.
Heat Capacity Calculator — Calculate heat energy Q = mcΔT, heat capacity, and heating time. Compare specific heats of common materials. Includes energy cost estimation and unit conversions.
Gauss's Law Calculator — Calculate electric flux and electric field using Gauss's law Φ = Q/ε₀. Supports spherical, cylindrical, and planar symmetries with dielectric materials.
Hohmann Transfer Orbit Calculator — Calculate Δv, transfer time, and propellant mass for Hohmann transfer orbits between two circular orbits. Supports Earth, Mars, Moon, and custom central bodies.
HP to Amps Calculator — Convert horsepower to amps for single-phase and three-phase motors. Accounts for motor efficiency and power factor. Includes NEMA reference tables.
Inductive Reactance Calculator — Calculate inductive reactance X_L = 2πfL, impedance, phase angle, and Q factor. Frequency response table shows how inductors behave across frequencies.
Ideal Transformer Calculator — Calculate transformer voltage, current, and turns ratio using V₁/V₂ = N₁/N₂. Step-up, step-down, impedance matching. Includes efficiency and power loss.
J-Pole Antenna Calculator — Calculate J-pole antenna dimensions for any frequency. Get radiator length, stub length, gap, and feed point for VHF/UHF bands.
Internal Resistance Calculator — Find battery or source internal resistance from open-circuit and loaded voltage. Includes power loss, efficiency, short-circuit current, and maximum power transfer analysis.
LC Filter Calculator — Design LC low-pass and high-pass filters. Calculate inductance, capacitance, cutoff frequency, and Butterworth component values up to 5th order.
kVA to Amperage Calculator — Convert kVA to amps for single-phase and three-phase systems. Includes power factor, wire sizing, breaker selection, and power triangle.
LED Resistor Calculator — Calculate the correct resistor value for any LED circuit. Supports series and parallel configurations, multiple LEDs, and nearest E24 standard values.
Magnetic Declination Calculator — Calculate magnetic declination for any location and date. Convert between true north and magnetic north bearings with compass correction.
Magnetic Dipole Moment Calculator — Calculate magnetic dipole moment, axial and equatorial fields, torque, and potential energy for current loops and coils.
Magnetic Field of Straight Wire Calculator — Calculate the magnetic field around a current-carrying wire using the Biot-Savart law. Supports infinite and finite wire models with permeability.
Magnetic Permeability Calculator — Calculate magnetic permeability, flux density, and core amplification. Compare diamagnetic, paramagnetic, and ferromagnetic materials.
Magnetic Moment Calculator — Calculate magnetic moment, torque, and potential energy for current loops in external fields. Supports circular, square, and rectangular loops.
MOSFET Threshold Voltage Calculator — Calculate MOSFET threshold voltage, drain current, operating region, transconductance, and overdrive voltage for NMOS and PMOS enhancement-mode transistors.
Natural Frequency Calculator — Calculate natural frequency, angular frequency, damping ratio, and period for spring-mass, pendulum, LC circuit, and cantilever beam systems.
Ohm's Law Calculator — Calculate voltage, current, resistance, and power with Ohm's Law. Includes energy cost estimation, AWG wire gauge recommendation, complete formula reference table, and collapsible wire sizing chart.
Parallel Capacitor Calculator — Calculate total capacitance for 2-10 capacitors in parallel, with reactance, energy storage, charge, and comparison to series configuration.
Parallel Inductors Calculator — Calculate total inductance for 2-6 inductors in parallel, with current distribution, reactance, energy storage, and mutual coupling analysis.
Parallel Resistor Calculator — Calculate total resistance for 2-10 resistors in parallel, with current distribution, power budget, nearest E24 standard value, and series comparison.
Porosity & Permeability Calculator — Calculate flow rate, Darcy velocity, pore velocity, and hydraulic conductivity using Darcy's law for porous media. Includes Kozeny-Carman estimation.
RC Circuit Calculator — Calculate RC time constant, charging/discharging curves, frequency response, energy storage, and settling time for resistor-capacitor circuits.
RC Filter Calculator — Design low-pass and high-pass RC filters with cutoff frequency, frequency response table, gain/phase analysis, and multi-stage cascading support.
Resistor Color Code Calculator — Decode 4, 5, or 6-band resistor color codes to find resistance, tolerance, and temperature coefficient. Visual resistor diagram included.
Resistor Wattage Calculator — Calculate power dissipated by a resistor and find the correct wattage rating. Includes derating curves, safety factors, and standard ratings.
Resistor Noise Calculator — Calculate Johnson-Nyquist thermal noise voltage and current for any resistor. Includes spectral density, SNR, and noise vs. bandwidth tables.
RLC Circuit Calculator — Analyze RLC series and parallel circuits. Calculate impedance, phase, resonant frequency, Q factor, damping ratio, and frequency response with voltage distribution tables.
Resonant Frequency (LC) Calculator — Calculate LC tank circuit resonant frequency, quality factor, bandwidth, and characteristic impedance. Includes frequency sweep table and Q factor visualization.
RLC Impedance Calculator — Calculate RLC circuit impedance Z = √(R² + (X_L − X_C)²), phase angle, current, power factor, and voltage distribution with impedance triangle visualization.
RMS Voltage Calculator — Calculate RMS voltage from peak voltage for sine, square, triangle, sawtooth, and rectified waveforms. Includes form factor, crest factor, and waveform comparison table.
Series Inductors Calculator — Calculate total inductance of series-connected inductors with optional mutual inductance. Supports up to 8 inductors with aiding/opposing coupling and parallel equivalent comparison.
Rolling Resistance Calculator — Calculate rolling resistance force F = C_rr × N for vehicles. Includes tire type and surface material comparison, grade resistance, power requirements, and per-tire force breakdown.
Series Resistor Calculator — Calculate total resistance of series resistors with voltage division. Supports up to 8 resistors with voltage drops, power dissipation, and visual breakdown of each resistor.
SLED (Superluminescent LED) Calculator — Calculate SLED characteristics including spectral width, coherence length, power spectral density, coupling efficiency, and wall-plug efficiency with source comparison table.
Solenoid Magnetic Field Calculator — Calculate magnetic field B = μ₀nI inside a solenoid. Includes field intensity H, magnetic flux, inductance, stored energy, field strength scale, and parameter sensitivity table.
Solenoid Inductance Calculator — Calculate solenoid inductance L = μ₀μᵣN²A/l with Nagaoka correction. Compare core materials, view scaling relationships, and compute magnetic field and stored energy.
Spherical Capacitor Calculator — Calculate capacitance of a spherical capacitor from inner/outer radii and dielectric. Includes charge, energy, E-field, surface charge density, cross-section visual, and dielectric comparison table.
Sound Wavelength Calculator — Calculate sound wavelength from frequency or vice versa. Supports 9 media (air, water, steel, etc.), temperature correction, musical note presets, and a multi-media comparison table.
Thermal Resistance Calculator — Calculate thermal resistance for up to 6 stacked layers. Includes temperature profile, layer breakdown, heat flux, status indicator, and presets for CPU, LED, and MOSFET thermal paths.
Transformer Sizing Calculator — Size a transformer by specifying voltages, power, and frequency. Calculates turns ratio, core area product, wire gauge, flux density margin, and compares 5 core materials.
Voltage Drop Calculator — Calculate voltage drop in electrical wiring by AWG, distance, current, and conductor material. NEC compliance check, AWG comparison table, power loss, and transmission efficiency.
Voltage Divider Calculator — Calculate output voltage from R1/R2 or design resistor values for a target voltage. Features load analysis, E24 nearest values, tolerance sensitivity, ratio visual, and common presets.
Voltage Regulation Calculator — Calculate voltage regulation percentage, output impedance, and power loss. Measure mode analyzes supply quality; design mode computes LDO requirements. Includes regulation quality rating and load s...
Volts to Electron-Volts Calculator — Convert between electron-volts, joules, temperature, and photon wavelength. Includes voltage-to-energy conversion, particle rest mass table, relativistic speed calculation, and 10 energy units.
Watt Calculator — Calculate electrical power in watts using multiple formulas: P=VI, P=I²R, P=V²/R, P=E/t, or P=τω. Includes energy cost estimation, unit conversions, and power scale comparison.
VSWR Calculator — Calculate VSWR, return loss, reflection coefficient, and mismatch loss. Input from VSWR, impedance, or return loss. Power distribution visual and comprehensive reference table.
Watt-Hours Calculator — Calculate energy in watt-hours from power and time, Ah and voltage, or estimate battery run time and required capacity. Includes DoD, efficiency, cost estimation, and battery comparison visual.
Watt Converter — Convert between 16 power units: watts, kilowatts, megawatts, horsepower (mechanical, metric, boiler), BTU/hr, dBm, dBW, calories/sec, and more. Log-scale power comparison visual.
Watts to Heat Calculator — Convert electrical power to heat output and calculate temperature rise in materials. Supports air, water, metals, oil. Includes heating rate, time to target temperature, timeline visual, and materi...
Watts to Amps Calculator — Convert watts to amps for DC, single-phase, and three-phase AC circuits. Includes power factor, NEC breaker sizing, wire gauge recommendation, voltage drop check, and appliance reference table.
Watts to Lux Calculator — Convert electrical watts to illuminance (lux) or calculate watts needed for target lux. Supports 10 light sources, utilization/maintenance factors, lux scale visual, and source comparison table.
Wavelength Calculator — Calculate wavelength from frequency or frequency from wavelength. Supports all EM spectrum bands, refractive index, photon energy, wave number. Includes spectrum visual and reference table.
Wire Resistance Calculator — Calculate wire resistance from AWG gauge or diameter, length, material, and temperature. Supports 7 conductor materials, temperature correction, cmil conversion. Includes temp effect visual and AWG...
Wavelength to Frequency Calculator — Convert wavelength to frequency for any EM radiation. Supports pm to km, 8 wavelength units, photon energy, wave number, visible color identification. Includes spectrum visual and conversion tables.
Wire Size Calculator — Calculate the correct wire gauge (AWG) for any circuit. Factors in ampacity, voltage drop, NEC continuous load rule, conduit fill derating, and insulation rating. Includes NEC ampacity table and de...