Basic calculations

Alternating current, impedance, reactance calculations

Signals, systems
Decibel, power ratio calculations

Inductors

Capacitors

Integrated circuits, oscillators, timers

Thermals

This tool is provided without any warranty.
Supported suffixes:
Suffixes are automatically added to the result
 f p n u m c k M G T P femto pico nano micro milli centi (none) kilo mega giga tera peta 10-15 10-12 10-9 10-6 10-3 10-2 100 103 106 109 1012 1015

For squared values (for example areas), only the following suffixes are supported: u, m, c, k, M

## Ohm's law

Enter two values, the third one will be calculated
R = V/I
 Voltage V Resistance Ω Current A

## Power (for DC circuits)

Enter two values, the third one will be calculated
P = V*I
 Voltage V Current A Power W

## Power (for DC circuits)

Enter two values, the third one will be calculated
P = V*I*cos(φ)
Q = V*I*sin(φ)
|S| = V*I
 Input values: Voltage V Current A Phase angle degrees radians Output values: Real (active) power W Reactive power var Apparent power VA

## E6/E12/E24 series (IEC 60063 standard)

 Input values: Value Series: E6 E12 E24 Output values: Closest lower or equal match Closest higher or equal match Closest match

## LED resistor calculator

R = (VIN-VLED)/ILED
* with nearest bigger resistor
 Input values: Desired current A Input voltage V LED voltage V Resistor series: Don't care E6 E12 E24 Output values: Calculated resistance Ω Calculated dissipation W Nearest bigger resistor: Ω New LED current*: A

## Capacitance / 3 digit code conversion

Enter either capacitance or code, the other value will be auto-calculated
Allowable range: 10pF to 99mF (although capacitors bigger than 10uF usually aren't marked this way)
 Code Capacitance F
 Letter B C D F G J K M Z Tolerance ±0.1pF ±0.25pF ±0.5pF ±1% ±2% ±5% ±10% ±20% +80, -20%

## Capacitor reactance

Enter two values, the third one will be calculated
XC = 1/(2*π*f*C)
 Capacitance F Frequency Hz Reactance Ω

## Inductor reactance

Enter two values, the third one will be calculated
XL = 2*π*f*L
 Inductance H Frequency Hz Reactance Ω

## RLC circuit impedance

XL = 2*π*f*L
XC = 1/(2*π*f*C)
Serial:
|Z| = sqrt(R2+(XL-XC)2)
If XL>XC, φ = arccos(R/|Z|)
If XL<XC, φ = -arccos(R/|Z|)
Parallel:
|Z| = 1/sqrt(1/R2+(1/XL-1/XC)2)
φ = arctan(R/(1/(1/XL-1/XC)))
 Input values: Resistance Ω Inductance H Capacitance F Frequency Hz Type: Parallel Serial Output values: Capacitor reactance Ω Inductor reactance Ω Impedance Ω Imaginary impedance part Ω Phase shift rad Phase shift °

## Resonant frequency

Enter two values, the third one will be calculated.
fres = 1/(2*π*sqrt(L*C))
 Inductance H Capacitance F Frequency Hz

## Critical damping (aperiodic) resistor for RLC circuit

Input values:
Q ≤ 0.5 (R/Z0 for parallel circuit, Z0/R for series circuit)
Result:
 Inductance H Capacitance F Type: Parallel Serial Resistance: 0Ω

## Capacitor peak dv/dt, peak current

Enter two values, the third one will be calculated.
Imax = C*(dV/dt)max
 Capacitance F dv/dt V/μs Max. current A

## Sine wave dv/dt (di/dt)

Enter two values, the other one will be calculated.
(dv/dt) = 2*π*f*Vp
 Amplitude V (A) dv/dt or di/dt V/s (A/s) Frequency Hz

## Sine wave amplitude ↔ RMS

Enter one value, the other one will be calculated.
Vpk = sqrt(2)*Vrms
 Amplitude V (A) RMS V (A)

## Rise time, bandwidth

Select encoding/use, enter one value, the other one will be calculated.
Assuming first order system, 3 dB permissible attenuation at max. frequency, 10% to 90% rise time, some rounding is done.
NRZ/RZ = (Non) Return-To-Zero tr = 0.35/BW (RZ), 0.7/BW (NRZ).
 Encoding/use (RZ/NRZ/analog): Analog circuits or RZ encoding NRZ encoding Rise time s Bandwidth/max. freq.: Hz/Baud

## RC low-pass filter

Enter three values, the fourth one will be calculated.
 Input/output values: Resistance Ω Capacitance F Frequency Hz Attenuation dB Output values: Phase angle °

## RC high-pass filter

Enter three values, the fourth one will be calculated.
 Input/output values: Resistance Ω Capacitance F Frequency Hz Attenuation dB Output values: Phase angle °

## Power ratio / decibel conversion

Input one value, the other one will be calculated. ratio (dB) = 10*log10(ratio)
 Power ratio dB

## Voltage ratio / decibel conversion

Enter one value, the other one will be calculated.
ratio (dB) = 20*log10(ratio)
 Voltage ratio dB

## Power / dBm conversion

Enter one value, the other one will be calculated.
P = 10((PdBm-30)/10)
 Power W dBm

## Inductor current rise

ΔI = V*ΔT/L
 Input values: Inductance H Voltage V Δ time s Output values: Δ current A

## Toroid inductance/turns

Enter either inductance or turn count, the other value will be automatically calculated.
L = μrμ0*N2*S/(π*d)
 Input values: Permeability Relative Absolute Permeability Outer diameter m Inner diameter m Height m Cross section Square Circular (circular cross-section is calculated from the diameters) Input/output values: Inductance H Turns

## Capacitor voltage rise

ΔV = I*ΔT/C
 Input values: Capacitance F Current A Δ time s Output values: Δ voltage V

## Capacitance

Enter three values, the other one will be calculated.
C = εrε0*S/l
 Permittivity Relative Absolute Permittivity Area m2 Distance m Capacitance F

## Capacitor charge

Enter five values, the other one will be automatically calculated
τ = R*C
ttotal = τ*ln((Vsupply-Vinitial)/(Vsupply-Vfinal))
Vfinal = Vinitial+(Vsupply-Vinitial)*(1-e-t/τ)
 Input/output values: Capacitance F Resistance Ω Supply voltage V Initial voltage V Final voltage V Time s Output values: Tau constant Initial current A Final current A

## Capacitor discharge

Enter four values, the other one will be automatically calculated
τ = R*C
Vfinal = Vinitial*e-t/τ
 Input/output values: Capacitance F Resistance Ω Initial voltage V Final voltage V Time s Output values: Tau constant Initial current A Final current A

## Capacitor stored energy

Enter two values, the third one will be automatically calculated
E = C*V2/2
 Capacitance F Voltage V Energy J

## ESR ↔ tan δ

Enter the frequency, capacitance and either ESR or tan δ
ESR = XC*tanδ
 Frequency Hz Capacitance F ESR Ω tan δ [0-1]

## Two transistor astable multivibrator

τ1 = R2*C1
τ2 = R3*C2
t1 = (ln(1-VCC/(VBE-VCC))-ln(VCC/VBE))*τ1
t2 = (ln(1-VCC/(VBE-VCC))-ln(VCC/VBE))*τ2
f = 1(t1+t2)
Schematic
 Input values: R2 Ω R3 Ω C1 F C2 F Voltages: Ignore Use during calculation VBEsat V VCC V Output values: Frequency Hz HIGH time s LOW time s

## Astable 555 frequency/duty cycle

A duty cycle lower than 50% can be achieved by connecting a diode in parallel to R2.
(Vctrl = Control voltage % / 100)
TLOW = -ln(1/2)*R2*C
No diode parallel to R2: THIGH = (ln(1-(1/2*Vctrl)) - ln(1-Vctrl))*(R1+R2)*C
Diode parallel to R2 (anode on pin 7): THIGH = (ln(1-(1/2*Vctrl)) - ln(1-Vctrl))*R1*C
T = TLOW+THIGH
f = 1/T
Duty% = 100*THIGH/T
 Input values: R1 Ω R2 Ω C F Diode parallel to R2 no yes Control voltage % of VCC Output values: Frequency Hz HIGH time s LOW time s Duty cycle %

## Monostable 555 period

Vctrl = Control voltage % / 100
T = -ln(1-Vctrl)*R*C
 Input values: Resistor: Ω Capacitor: F Control voltage % of VCC Output values: Period: s

## IR(S)2153(1)(D) frequency

f = 1/(1.4*(Rt+75)*Ct)
 Input values: Timing resistor: Ω Timing capacitor: F Output values: Frequency Hz

## UC3842, UC3843, UC3844, UC3845 frequency

The result may not be accurate if the timing resistor is lower than 5kΩ
fosc = 1.8/(Rt*Ct)
 Input values: Timing resistor: Ω Timing capacitor: F Chip: UC3842/UC3843 UC3844/UC3845 Output values: Oscillator frequency Hz Output frequency Hz

## TL494/KA7500 frequency

fosc = 1/(Rt*Ct)
 Input values: Timing resistor: Ω Timing capacitor: F Mode: Single ended Push-pull Output values: Oscillator frequency Hz Output frequency Hz

## Voltage regulator feedback

Enter three values, the other one will be auto-calculated
Vout = Vref*((R2/R1)+1)
 Chip Voltage LM317T 1.25V MC34063 1.25V LM2576-ADJ 1.23V LM2596-ADJ 1.23V UC384x (VFB) 2.5V
 R1: Ω (reference) R2: Ω Reference voltage: V Output voltage: V

## MOSFET, IGBT, diode switching loss calculator, SEMIKRON AN1403 method

Calculate conduction loss separately (approximately IRMS*resistance for FETs, or IAVG for diodes and IGBTs). Gate drive loss is neglected.
The "scaling factor" is not included in the Semikron PDF. According to simulations, if a MOSFET has a certain switching loss with certain gate drive resistance (external+internal gate resistance) and it is doubled, the loss will be also roughly doubled (Ks≈2). The MOSFET coefficients also aren't present in the original PDF and were determined empirically through simulations. Switch and diode losses must be calculated separately.
Calculate turn-on and turn-off losses separately and add the results. Diode turn-on losses are usually neglectable compared to conduction and turn-off.

Psw = f*Eref*(I/Iref)Ki*(U/Uref)Ku*(1+Kt*(T-Tref))*Ks
 Part type: Typical IGBT (Ki=1, Kv=1.3, Kt=0.003) Typical MOSFET (Ki=1, Kv=1.15, Kt=0.008) Typical diode (Ki=0.5, Kv=0.6, Kt=0.006) Use custom coefficients Select "custom" to adjust Kx Switching loss (energy) at Vref, Iref J Reference current A Reference voltage V Reference temperature: °C Current: A Voltage: V Junction temperature: °C Frequency: Hz Custom Ki: Custom Kv: Custom Kt: Scaling factor: Power loss: 0W

## MOSFET switching loss estimation

Calculate conduction loss separately (approximately IRMS*resistance for FETs, or IAVG for diodes and IGBTs).
Switch and diode (internal diode - if it conducts) losses must be also calculated separately.
Don't forget to add prefixes, times are usually in nanoseconds.
The gate resistance effect (tr, tf depend on Rg) calculation is usable only if the gate drive voltage is close to the reference.
If only a light load is switched at a high frequency, it might be a good idea to add the D-S capacitance discharge loss.
The coefficients were determined theoretically by linearizing the waveform and integrating instantaneous power through the switching times while rising/falling. Select "Custom" in dropdown menus to use custom Kl.

Kg = (Rg_int+Rg_ext)/(Rg_int+Rg_ext_ref)
Ecap = 0,5*Coss*Vds_off2
Esw_on = Kc*Kg*Kl*tr*Vds_on*Id_on
Esw_off = Kc*Kg*Kl*tf*Vds_off*Id_off
Psw = f*(Ecap+Esw_on+Esw_off)
 Switching frequency Hz Reference rise time s Reference fall time s Turn-on drain-source voltage V Turn-on drain current A Turn-off drain-source voltage V Turn-off drain current A Consider gate resistor: Consider gate resistance effect on tr, tf Neglect gate resistance effect on tr, tf External gate resistance Ω Reference ext. gate resistance Ω Internal gate resistance Ω Consider Cds: Consider drain-source capacitance Neglect drain-source capacitance Drain-source capacitance F Turn-on load: Resistive (Kl≈0.17) Inductive/Constant current (Kl≈0.5) Custom coefficient Turn-off load: Resistive (Kl≈0.17) Inductive/Constant current (Kl≈0.5) Custom coefficient Custom Kl coefficient, turn-on Custom Kl coefficient, turn-off Custom Esw scaling factor KC: Power loss: 0W

## MOSFET/IGBT gate drive loss

Pgd = f*Vgs_s*Qg
 Frequency: Hz Gate voltage swing: V Gate charge: C Power loss: 0W

## MOSFET, IGBT, diode, resistor conduction loss calculator

Enter only values related to the waveform and part type
This function (conduction loss for various waveforms) is still UNDER CONSTRUCTION and might not be accurate.
PD,IGBT = Vdrop*IARV
PMOSFET = R*I2RMS
Table
* this is only a fairly rough estimation (error ≤6.7%), valid only for Imt<5*Ims
Multiply RMS value of sine/triangle by sqrt(2) to get RMS value of half-rectified sine/triangle
 Waveform IRMS IARV Sine 0.7071*Im 0.6366*Im Triangle 0.5774*Im 0.5*Im Square, D=0 to 1 sqrt(D*Ihigh2+(1-D)*Ilow2) D*Ihigh+(1-D)*Ilow Superposed triangle and sine, min. at t=0 sqrt((0.5372*Imt+0.7071*Ims)^2+(0.0699*Imt)^2) 0.6366*Ims+0.5*Imt Superposed triangle and sine, tri. +max. at t=0 sqrt((0.5774*Imt)^2+(0.7071*Ims)^2) * Ims*(0.62+0.2338*(Imt/Ims)+0.0403*(Imt/Ims)2-0.002*(Imt/Ims)3)
 Part type: Diode/IGBT (consider constant V) MOSFET (consider constant R) Waveform: Rectangular wave with given duty cycle Sine wave Half rectified sine wave Triangle wave Half rectified triangle wave Superposed sine and triangle, both minimums at t=0 Superposed half-sine and half-triangle, both minimums at t=0 Superposed half-sine and half-triangle, triangle maximum at t=0 Custom average current (for IGBT/D) or RMS current (for MOSFET) Rectangular wave, low current: A Rectangular wave, high current: A Rectangular wave, duty cycle: % Sine/half-sine current amplitude: A Triangle/half-triangle current amplitude: A Custom RMS current: A Custom average rectified current: A MOSFET on-state/resistor resistance: Ω IGBT/Diode voltage drop: V Power loss: 0W

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Function list:
• basic calculations (DC power, AC power, LED resistor, Ohm's law, E6/E12/E24 series selector)
• capacitor reactance, inductor reactance, RLC impedance, aperiodicity, resonant frequency calculation
• capacitor dv/dt, maximum current calculation, tan delta to ESR converter
• rise time ↔ bandwidth calculator
• decibel to ratio conversions
• toroid inductance calculator
• capacitor energy and voltage rise
• 555, TL494, UC384x calculator
• MOSFET, IGBT, diode switching and conduction loss calculator