Electrical calculators
Works in your browser. Nothing is uploaded.SMD codes
Read the code printed on an SMD resistor or capacitor, or type a value to see how it is marked.
Resistance
–
How it’s written
–
3-digit code–
4-digit code–
EIA-96 code–
Picofarad code–
Letter code–
In pF · nF · µF–
Rated voltage–
Tolerance–
R marks the point: 4R7 is 4.7 Ω. In an EIA-96 code the two digits pick a precision value and the letter multiplies it: Z ×0.001, Y or R ×0.01, X or S ×0.1, A ×1, B or H ×10, C ×100, D ×1000, E ×10 000, F ×100 000.
The code is in picofarads: 104 is 10 and four zeros, 100 000 pF. A leading code such as 2A gives the voltage, a trailing letter such as J the tolerance.
Electrical calculators
Resistor color codeBands to ohms and back.Ohm’s law and powerVolts, amps, ohms and wattsVoltage drop and cable sizeThe drop over a run, and the smallest cable within itWire sizesAWG, mm², kcmil and diameterLED resistorThe resistor an LED needsSMD codesResistor and capacitor markings555 timerAstable and monostableBattery runtimeHow long a battery lasts
How to use it
- Pick the part
Resistor or capacitor.
- Type the code
As printed: 103, 1002, 4R7 or 01C on a resistor, 104 or 4n7 on a capacitor.
- Or type a value
Like 4.7k or 100n, to see every code that marks it.
Tips
- R is the point
4R7 is 4.7 Ω and R47 is 0.47 Ω. A part marked 000 is a zero-ohm link.
- Use a magnifier
On small parts 6, 8 and 0 look alike. Your phone’s camera, zoomed in, helps.
- Unmarked capacitors
Most small ceramic capacitors carry no code at all. Measure them, or check the parts list.
In the app
Electrical calculator in Angle Meter
- Resistor color code, 4, 5 and 6 bands
- Codes typed as printed on the part
- LED resistor, 555 timer and dividers
- Connector pinouts and IP ratings
Get it onGoogle PlayComing soon to the App Store
Electrical calculator guide ›