Basic Circuit Laws 10
- Current Divider CalculatorCalculatorHow a current splits between resistors in parallel: the current in every branch, its share as…
- Delta-Wye Transformation CalculatorCalculatorConvert a three-terminal resistor network between its delta (Δ, mesh) and wye (Y, star) forms in…
- Load Line CalculatorCalculatorThe graphical method that explains every nonlinear-device bias problem: a device's own I-V curve crossed with…
- Ohm’s Law CalculatorCalculatorEnter any two of voltage, current, resistance and power and get the other two, with units…
- Resistor Power Rating CalculatorCalculatorThe power a resistor really dissipates from its resistance and either the voltage across it or…
- Series and Parallel Resistor CalculatorCalculatorTotal resistance of up to six resistors in series or in parallel, with the voltage across…
- Thévenin and Norton Equivalent CalculatorCalculatorReplace a source and its resistor network with one voltage source and one resistance — or…
- Two-Loop Mesh Current CalculatorCalculatorTwo loops with their own sources and a resistor in common, solved by Kirchhoff's voltage law…
- Voltage Divider CalculatorCalculatorOutput voltage of a two-resistor divider, how much a load pulls it down, the current and…
- Wheatstone Bridge CalculatorCalculatorThe general four-arm bridge: the exact output voltage when it is out of balance, the balance…
Batteries, UPS & Solar 14
- Battery C-Rate CalculatorCalculatorC-rate to current and current to C-rate, and then the part the arithmetic hides: the capacity…
- Battery Charging Time CalculatorCalculatorHow long a battery takes to charge from its capacity, the charger's current or power and…
- Battery Life CalculatorCalculatorHow long a battery will run a load: from its capacity in mAh, Ah or Wh,…
- Coin Cell Battery Life CalculatorCalculatorLife of a duty-cycled sensor node on a coin cell, with two active phases and the…
- Inverter / UPS Size Calculator (VA)CalculatorAdd up to six appliances, mark the ones with a motor, and get the running watts,…
- Inverter Battery Backup Time CalculatorCalculatorHow many hours your inverter will run on its battery: from the bank's Ah and voltage,…
- Lithium Pack Builder CalculatorCalculatorAn S×P pack worked out from one cell's datasheet: pack voltage full, nominal and empty, amp-hours…
- Power Bank Real Capacity CalculatorCalculatorWhy a 20,000 mAh power bank does not charge a 5,000 mAh phone four times: the…
- PV I-V Curve CalculatorCalculatorThe single-diode model, with its parameters extracted from a module's data sheet rather than asked for:…
- Solar Battery Size CalculatorCalculatorThe battery bank an off-grid or backup system needs: from the daily load in watt-hours, the…
- Solar Charge Controller Size Calculator (PWM / MPPT)CalculatorThe controller your array needs: minimum current from the panels' short-circuit rating with the 125% factor,…
- Solar Panel Size CalculatorCalculatorHow many kilowatts of panels your house needs: from your daily units, the peak sun hours…
- Solar Panel Tilt Angle CalculatorCalculatorThe best fixed tilt for your latitude, and — computed rather than asserted — the share…
- Solar String Voc CalculatorCalculatorBoth ends of a grid-tie string: the most modules in series before the coldest morning's open-circuit…
Capacitors, Inductors & Reactance 9
- Air-Core Inductor Calculator (Single-Layer Coil)CalculatorInductance of a single-layer air-cored coil from its diameter, length and turns by Wheeler's 1928 formula…
- Capacitive and Inductive Reactance CalculatorCalculatorReactance of a capacitor or an inductor at any frequency — X_C = 1/(2πfC), X_L =…
- Capacitor Energy and Backup Time CalculatorCalculatorEnergy stored in a capacitor in joules, watt-hours and milliamp-hours — and the question people actually…
- Capacitor Ripple Current and ESR CalculatorCalculatorWhat ripple current does to an electrolytic: the power its ESR dissipates, the core temperature that…
- Capacitor Self-Resonance CalculatorCalculatorEvery capacitor is a series R-L-C, and above its self-resonant frequency it is an inductor. This…
- LC Resonant Frequency CalculatorCalculatorResonant frequency of an LC tank from the inductance and capacitance — or the capacitor you…
- MLCC DC Bias Derating CalculatorCalculatorWhat is left of a ceramic capacitor once the DC bias, the temperature, the ageing and…
- RC and RL Time Constant CalculatorCalculatorThe time constant τ of a resistor-capacitor or resistor-inductor circuit, how far it has charged or…
- Tantalum Capacitor Derating CalculatorCalculatorTantalums fail short and a shorted one in a low-impedance circuit can ignite, and every published…
Component Codes & Values 4
- Capacitor Code CalculatorCalculatorDecode the three-digit value code printed on ceramic and film capacitors (104 = 100 nF), the…
- Inductor Color Code CalculatorCalculatorRead a four-band moulded inductor — two digits, a multiplier and a tolerance, in microhenries —…
- Resistor Color Code CalculatorCalculatorPick the colour of each band on a 4-, 5- or 6-band resistor and read its…
- SMD Resistor Code CalculatorCalculatorRead the marking on a surface-mount resistor — 473, 4702, 4R7 or the three-character EIA-96 code…
DC-DC Converters 11
- Boost Converter DesignerConverterDesign the power stage of a step-up (boost) converter: duty cycle, inductance, input and peak currents,…
- Buck Converter DesignerConverterDesign the power stage of a step-down (buck) converter: duty cycle, inductance, peak and RMS currents,…
- Buck-Boost Converter DesignerConverterDesign an inverting buck-boost converter, which makes a negative output from a positive input: duty cycle,…
- Charge Pump CalculatorCalculatorSwitched-capacitor voltage doubler, inverter and n-stage Dickson multiplier: the output voltage under load, the ripple, the…
- Ćuk Converter DesignerConverterDesign an inverting Ćuk converter: duty cycle, both inductors, the coupling capacitor's voltage, ripple and RMS…
- DC-DC Efficiency Curve CalculatorCalculatorAssemble a buck converter's whole loss budget against load — MOSFET conduction and switching, gate drive,…
- Flyback Converter CalculatorConverterFirst-pass flyback design from the input range, output and switching frequency: turns ratio, reflected voltage, primary…
- Forward Converter CalculatorConverterDesign a single-switch forward converter with a reset winding: turns ratio, duty cycle across the input…
- Push-Pull Converter CalculatorConverterCentre-tapped push-pull power stage: turns ratio, the duty cycle per switch and the dead time between…
- SEPIC Converter DesignerConverterDesign a SEPIC: the one switching topology that steps up or down from the same circuit…
- Soft-Start Capacitor CalculatorCalculatorThe capacitor on a regulator's soft-start pin, the ramp time it gives and — the part…
EMI, EMC & Filters 14
- Bonding Strap Impedance CalculatorCalculatorA bonding strap is meant to hold two pieces of metal at the same potential, and…
- Cable Radiated Emissions CalculatorCalculatorThe common-mode current an RE102 limit actually permits — usually a couple of microamps — and…
- Cable Shield Transfer Impedance CalculatorCalculatorHow much voltage a shield current puts onto the inner conductor, per metre — and what…
- Conducted Emissions Margin CalculatorCalculatorHow far under a conducted-emissions limit your measured or predicted spectrum sits, at every frequency you…
- Converter Conducted Emissions EstimatorConverterThe differential-mode conducted noise a switching converter will produce before the hardware exists, from the shape…
- EMI Filter Designer CalculatorCalculatorSize the X capacitor, the Y capacitors and the common-mode choke of a single-stage input filter,…
- EMI Filter Insertion Loss CalculatorCalculatorWhat a built filter really does, once the capacitor's ESL and the choke's winding capacitance are…
- Enclosure Aperture Leakage CalculatorCalculatorWhat a shielded box actually leaks through its slots, seams, display cut-outs and vents — the…
- Field Strength and Power Density ConverterConverterElectric field, magnetic field, power density, received power and antenna factor at a point — each…
- Ground Loop Coupling CalculatorCalculatorTwo mechanisms that get called the same thing and are not. Common-impedance coupling, where a noisy…
- Radiated Emissions Margin CalculatorCalculatorHow far under a radiated-emissions limit your measured or predicted electric field sits, at every frequency…
- RS103 Test Field CalculatorCalculatorWhat amplifier an RS103 radiated-susceptibility test needs: the forward power for a stated field at a…
- Shielding Effectiveness CalculatorCalculatorAbsorption, reflection and the multiple-reflection correction for a solid conductive wall, with the wave impedance taken…
- Y Capacitor Limit CalculatorCalculatorHow large a Y capacitor you are permitted, which is almost never the size you want…
Electrical Unit Converters 4
- BTU to Watts Converter (and Tons of Refrigeration)ConverterBTU/h, watts, kilowatts, tons of refrigeration and kcal/h, all five at once and all from exact…
- Capacitance Converter (pF, nF, µF)ConverterConvert a capacitance between picofarads, nanofarads, microfarads, millifarads and farads — or start from the three-digit…
- HP to kW ConverterConverterConvert horsepower to kilowatts and back — with all three definitions kept apart, because mechanical, metric…
- mAh to Wh Converter (and Wh to mAh)ConverterConvert battery capacity between mAh, Ah and watt-hours at a stated cell voltage, with the energy…
Filters & Frequency Response 7
- Anti-Aliasing Filter CalculatorCalculatorHow much attenuation your anti-aliasing filter has to reach before anything folds back into the band…
- Control Loop Stability CalculatorCalculatorEnter a loop gain — a DC or integrator term, a resonant pole pair, zeros and…
- EMI Input Filter CalculatorCalculatorThe LC filter in front of a switching converter, and the stability question that comes with…
- Filter Response Order CalculatorCalculatorGive a passband edge with an allowed droop and a stopband edge with a required attenuation,…
- Multiple-Feedback (MFB) Filter CalculatorCalculatorSecond-order low-pass or band-pass in the inverting multiple-feedback topology: the three resistors and two capacitors for…
- RC and RLC Filter CalculatorCalculatorCut-off or resonant frequency, Q and bandwidth of an RC low-pass or high-pass filter, a series…
- Sallen-Key Active Filter DesignerCalculatorSecond-order Sallen-Key low-pass or high-pass, unity-gain or equal-component, to a Butterworth, Bessel or 0.5 dB Chebyshev…
LEDs & Lighting 5
- LED Array Calculator (Series and Parallel Strings)CalculatorTurn a supply voltage, an LED forward voltage and a total LED count into a real…
- LED Series Resistor CalculatorCalculatorThe resistor an LED needs: exact value, the next standard value up, the current you actually…
- LED Strip Power Supply and Voltage Drop CalculatorCalculatorTotal power, supply current and the power supply size for a run of LED strip —…
- Lumens to Watts Converter (Luminous Efficacy)CalculatorLumens to watts and back through luminous efficacy, with typical figures for incandescent, halogen, CFL and…
- Room Lighting Calculator (Lux and Lumen Method)CalculatorThe lumen method, worked properly: room index, the total lumens a room needs at your target…
Linear Power & Regulators 3
- LDO Power Loss and Thermal CalculatorCalculatorWork out how much heat a linear regulator dissipates, its efficiency and junction temperature, and the…
- LM317 Voltage Regulator CalculatorCalculatorSet an LM317's output with R1 and R2, or work backwards from the voltage you want…
- Zener Diode Regulator CalculatorCalculatorSize the series resistor for a zener shunt regulator over its whole input and load range,…
Magnetics & Transformers 11
- B-H Curve and Core Loss CalculatorCalculatorThe hysteresis loop a core actually traverses at your drive level, drawn from an arctangent loop…
- Common Mode Choke CalculatorCalculatorCommon-mode inductance from turns and core, the leakage that is the only differential inductance the filter…
- Core Loss Calculator (Steinmetz)CalculatorPᵥ = k·fα·Bβ from a ferrite data sheet, times the effective core volume, with the copper…
- CT Burden Resistor CalculatorCalculatorSize the burden resistor on a split-core or toroidal current transformer so that full-scale primary current…
- Gapped Core Inductance CalculatorCalculatorEffective permeability, Aₗ and inductance for an inductor wound on a gapped ferrite core — with…
- Litz Wire and Skin Depth CalculatorCalculatorSkin depth first, because that is the number everything else hangs on — then the strand…
- SMPS Transformer CalculatorCalculatorSize a switch-mode transformer for a forward or flyback converter by the area-product method: the core…
- Toroid Inductor Turns Calculator (AL Value)CalculatorTurns for a target inductance on a ring core from its Aₗ value, both directions, with…
- Transformer Efficiency CalculatorCalculatorEfficiency and voltage regulation for a mains transformer from the figures it is actually specified by…
- Transformer kVA to Current CalculatorCalculatorFull-load current on both windings from a transformer's kVA rating — or the kVA from a…
- Transformer Turns Ratio CalculatorCalculatorTurns ratio, secondary voltage, current ratio, impedance ratio and volts per turn — solved whichever way…
Motors & Drives 14
- BLDC Inverter Loss CalculatorCalculatorLosses in a three-phase, six-MOSFET motor inverter with sinusoidal phase current: conduction, switching and dead-time diode…
- BLDC Motor Torque-Speed Envelope CalculatorCalculatorThe motor sizing plot: the continuous and peak torque a brushless machine and its drive can…
- DC Motor Calculator (Back-EMF, Kv and Torque)CalculatorThe brushed permanent-magnet motor from first principles: back-EMF from speed, current from what is left of…
- E-Bike Range CalculatorCalculatorHow far an e-bike battery goes, built from the physics rather than a lookup: rolling resistance,…
- Electromechanical Actuator Load Locus CalculatorCalculatorSize a linear electromechanical actuator against a sinusoidal command. The page sweeps one whole cycle, adds…
- Gear Ratio CalculatorCalculatorOverall ratio, output speed and output torque for one, two or three gear or belt stages,…
- Induction Motor Slip CalculatorCalculatorSynchronous speed from the supply frequency and the pole count, then the slip, the slip speed…
- Induction Motor Torque-Speed Curve CalculatorCalculatorThe whole torque-speed curve of a cage or wound-rotor induction machine from its equivalent-circuit parameters: starting…
- Motor Full Load Current CalculatorCalculatorFull-load amps from a motor's nameplate kW or HP, with efficiency and power factor in the…
- Motor Power, Torque and Speed CalculatorCalculatorAny two of shaft power, torque and speed give the third — in kW, HP, N·m,…
- Pump and Fan System Curve CalculatorCalculatorWhere a pump or fan actually operates: its own head-flow curve crossed with the system's resistance…
- Pump Motor Power CalculatorCalculatorHydraulic power, shaft power, motor input power, current and running cost from the flow and head…
- Regenerative Braking CalculatorCalculatorWhat happens when a motor becomes a generator: the braking torque and power, the energy that…
- Stepper Motor Speed, Torque and Steps CalculatorCalculatorSteps per revolution, rpm and the linear travel per step for a leadscrew or a belt…
Op-Amps & Analog 6
- BJT as a Switch Calculator (Base Resistor)CalculatorBase resistor for an NPN transistor switching a lamp, relay or motor from a microcontroller pin…
- BJT Biasing Calculator (Voltage-Divider Bias)CalculatorThe four-resistor bias that every small-signal transistor stage is built on: divider, emitter and collector resistors…
- Comparator Hysteresis (Schmitt Trigger) CalculatorCalculatorUpper and lower switching thresholds, hysteresis width and centre for a comparator with positive feedback —…
- Op-Amp Capacitive Load Stability CalculatorCalculatorWhy a buffer oscillates when you put a cable on it: the amplifier's open-loop output resistance…
- Op-Amp Inverting Amplifier CalculatorCalculatorGain, gain in decibels and output voltage of an inverting op-amp stage, whether the output clips…
- Op-Amp Non-Inverting Amplifier CalculatorCalculatorGain 1 + Rf/R1, gain in decibels, output voltage and rail clipping for a non-inverting op-amp…
PCB Design 8
- Crosstalk CalculatorCalculatorHow much of an edge on one trace appears on the one beside it: near-end and…
- Differential Pair Impedance CalculatorCalculatorDifferential, odd-mode, even-mode and single-ended impedance of an edge-coupled pair — microstrip or stripline — from…
- Microstrip Impedance CalculatorCalculatorCharacteristic impedance, effective permittivity, propagation delay and guided wavelength for a PCB microstrip from its width,…
- PCB Propagation Delay and Length Matching CalculatorCalculatorHow long a signal takes to get down a trace, on an outer layer or an…
- PCB Trace Resistance CalculatorCalculatorThe resistance of a copper trace from its length, width, copper weight and temperature — with…
- PCB Trace Width CalculatorCalculatorThe copper trace width a current needs for a chosen temperature rise, on an outer or…
- PCB Via Current CalculatorCalculatorHow much current a plated via barrel can carry for a temperature rise you choose, from…
- Stripline Impedance CalculatorCalculatorCharacteristic impedance, propagation delay and guided wavelength for a buried PCB trace between two reference planes…
Power Semiconductors & Thermal 11
- Component Derating CalculatorCalculatorDerating is running a part below its rating so that it survives. The factors live in…
- Conduction-Cooled Electronics CalculatorCalculatorIn vacuum there is no convection. A board that runs cool on the bench cooks in…
- Diode Power Loss CalculatorCalculatorEstimate a rectifier or freewheel diode's losses — conduction, reverse recovery and leakage — and its…
- Enclosure Fan Airflow Calculator (CFM)CalculatorHow much air a sealed-but-vented enclosure needs to carry its own heat away: Q = P…
- ESD and TVS Protection CalculatorCalculatorThe peak current an electrostatic discharge delivers, the voltage the TVS actually clamps to at that…
- Heatsink Thermal Resistance CalculatorCalculatorThe heatsink a power transistor, regulator or diode needs: the maximum sink-to-ambient thermal resistance (θSA) from…
- MOSFET Gate Driver Calculator (Power and Gate Resistor)CalculatorGate-drive power from Qg, Vgs and the switching frequency — and, more usefully, how it splits…
- MOSFET Loss CalculatorCalculatorEstimate a switching MOSFET's conduction, switching and output-capacitance losses from datasheet values, the gate-drive power, and…
- MOSFET Output Characteristics CalculatorCalculatorDrain current against drain-source voltage for a MOSFET at two gate voltages, with a resistive load…
- RC Snubber CalculatorCalculatorSize the R and C across a switching device or a relay contact from figures you…
- Switching Device Load Locus CalculatorCalculatorThe path a hard-switched device traces in the voltage-current plane over one cycle, drawn against the…
RF, Antennas & Transmission Lines 10
- Antenna Length CalculatorCalculatorFrequency to free-space wavelength, then the lengths you actually cut: a half-wave dipole and each of…
- Attenuator Calculator (Pi and T Pads)CalculatorResistor values for a Pi or T attenuator pad — for equal impedances or between two…
- Coax Impedance CalculatorCalculatorCharacteristic impedance of a coaxial cable from the inner conductor diameter, the dielectric diameter and its…
- dBm to Watts CalculatorCalculatorConvert between dBm, dBW and watts, milliwatts or microwatts — and the RMS, peak and peak-to-peak…
- Free Space Path Loss CalculatorCalculatorFree-space path loss in decibels from distance and frequency — or the range a given loss…
- Fresnel Zone CalculatorCalculatorThe first Fresnel zone radius anywhere along a radio path, the 60% of it that has…
- L-Network Impedance Matching CalculatorCalculatorMatch a source resistance to a load with two reactive parts: both L-network solutions (low-pass and…
- Link Budget CalculatorCalculatorTransmit power, antenna gains, cable losses, path loss and receiver sensitivity added up into a received…
- Smith Chart Impedance CalculatorCalculatorA load made of R, L and C, traced across a frequency band as a locus…
- VSWR and Return Loss ConverterCalculatorEnter any one of VSWR, return loss, reflection coefficient or mismatch loss and get the other…
Sensors & Thermistors 6
- 4–20 mA Loop CalculatorCalculatorConvert between loop current and engineering units either way, with the sense-resistor voltage, the ADC counts…
- Load Cell CalculatorCalculatorWhat a load cell gives you and what a converter can do with it: the output…
- NTC Thermistor CalculatorCalculatorResistance from temperature or temperature from resistance, with the Beta model or Steinhart–Hart coefficients — then…
- PT100 / PT1000 RTD CalculatorCalculatorTemperature to resistance and resistance back to temperature for a platinum RTD, using the Callendar–Van Dusen…
- Strain Gauge CalculatorCalculatorWhat a bonded strain gauge actually gives you: the resistance change for a strain, the Wheatstone…
- Thermocouple Calculator (Type K Voltage and Temperature)CalculatorBoth directions on the NIST ITS-90 reference functions — temperature to millivolts and millivolts back to…
Signals, Audio & Measurement 7
- ADC Resolution and LSB CalculatorCalculatorWhat one bit of an analogue-to-digital converter is actually worth: the LSB size, the number of…
- Decibel (dB) CalculatorCalculatorTurn a ratio into decibels or decibels back into a ratio, with the right factor —…
- Energy Meter Pulse (imp/kWh) CalculatorCalculatorTurn the blinks of an electricity meter's test LED into watts: the meter constant in imp/kWh…
- Oscilloscope Bandwidth and Rise Time CalculatorCalculatorRise time and bandwidth through the 0.35 constant — derived here from the single-pole step response…
- RMS, Peak and Peak-to-Peak ConverterConverterEnter any one of RMS, peak, peak-to-peak or rectified average and get the other three, for…
- Shunt Resistor CalculatorCalculatorFull-scale current and a target sense voltage give the shunt — and then everything that goes…
- Speaker Impedance Calculator (Series and Parallel)CalculatorTotal impedance of up to six drivers in series, in parallel or in series-parallel, the power…
Timers, Oscillators & Digital 7
- 555 Timer Astable CalculatorCalculatorFrequency, period, high and low times and duty cycle for a 555 in astable mode —…
- 555 Timer Monostable (One-Shot) CalculatorCalculatorPulse width of a 555 one-shot from R and C — or the resistor or capacitor…
- Crystal Load Capacitor CalculatorCalculatorThe two capacitors a Pierce oscillator needs, from the crystal's specified load capacitance and the stray…
- I²C Pull-Up Resistor CalculatorCalculatorThe window your I²C pull-ups have to sit in: the minimum set by the sink current…
- Logic Level Compatibility and Level Shifter CalculatorCalculatorWhether one device can drive another directly, in both directions, from the four numbers on their…
- PWM Duty Cycle and Average Voltage CalculatorCalculatorOn and off times, average voltage, RMS voltage and average power from a PWM frequency and…
- UART Baud Rate Error CalculatorCalculatorThe divisor your peripheral clock and target baud rate actually produce, the baud rate that comes…
Wiring, Cables & Home Electrical 12
- AC Tonnage Calculator (Room Size to Tons)CalculatorRoom size, people, sun, floor and climate to a cooling load in tons, kW and BTU/h…
- AWG Wire Size CalculatorCalculatorDiameter, cross-sectional area and resistance of any American Wire Gauge size from 4/0 to 40, for…
- Earthing / Grounding Resistance CalculatorCalculatorThe resistance of a driven rod by Dwight's formula, and of a row of rods with…
- Electricity Consumption Calculator (Units per Month)CalculatorAdd up to six appliances — watts, hours a day and how many you own —…
- Generator (DG) Size CalculatorCalculatorAdd up to six loads with their power factors and starting multiples and get the running…
- kVA to kW Calculator (and kW to kVA)CalculatorConvert apparent power to real power and back at any power factor, and get the full-load…
- MCB Size CalculatorCalculatorTurn a load in watts or amps into a design current and the next standard MCB…
- Power Factor and PF Correction Capacitor CalculatorCalculatorYour present power factor from kW and kVA — or from kW, volts and amps —…
- Three-Phase Power CalculatorCalculatorReal, reactive and apparent power from line voltage, line current and power factor — plus the…
- Voltage Drop CalculatorCalculatorThe voltage a cable loses at your load current — in volts and as a percentage…
- Watts to Amps Calculator (and Amps to Watts)CalculatorConvert power to current, or current to power, for DC, single-phase AC and three-phase AC —…
- Wire Size Calculator (Current and Voltage Drop)CalculatorThe smallest standard cable size that keeps the voltage drop within your limit, for DC, single-phase…
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