⚡ Electronics Calculators
Free online tools for hobbyists, students and makers — calculate values and see the circuit instantly.
Ohm's Law & Power Calculator
Enter any two values — the other two are calculated. V = I × R, P = V × I.
Series & Parallel Resistor Calculator
Series: R = R1 + R2 + … | Parallel: 1/R = 1/R1 + 1/R2 + …
Series & Parallel Capacitor Calculator
Parallel: C = C1 + C2 + … | Series: 1/C = 1/C1 + 1/C2 + … (opposite of resistors)
Resistor Color Code Calculator
Pick the band colors to read the resistor value.
LED Series Resistor Calculator
R = (Vsupply − Vled × n) / I — chooses the nearest standard E12 resistor and its power rating.
Voltage Divider Calculator
Vout = Vin × R2 / (R1 + R2). Leave one field empty (Vout or R2) to solve for it.
555 Timer Calculator
Astable (blinker / oscillator) or Monostable (one-shot delay).
RC Time Constant & Low/High-pass Filter
τ = R × C | Cut-off frequency fc = 1 / (2π R C)
Ceramic Capacitor Code Decoder
Enter the 3-digit code printed on the capacitor (e.g. 104, 223, 471). Optional tolerance letter (J, K, M).
| Code | Value | Code | Value |
|---|---|---|---|
| 101 | 100 pF | 103 | 10 nF |
| 102 | 1 nF | 104 | 100 nF (0.1 µF) |
| 222 | 2.2 nF | 105 | 1 µF |
| 473 | 47 nF | 225 | 2.2 µF |
SMD Resistor Code Calculator
Supports 3-digit (103), 4-digit (1002), R-notation (4R7) and EIA-96 (01C).
Battery Life Calculator
Estimated runtime = capacity / load current × efficiency factor (0.7 typical).
LM317 Adjustable Regulator Calculator
Vout = 1.25 × (1 + R2 / R1). Leave R2 empty to calculate it for a target voltage.
Results are theoretical — always allow for component tolerance. Need parts? Browse our shop for resistors, capacitors, LEDs and ICs.
