Electronics Calculator Toolbox

An electronics calculator for the workbench, and it works without a connection. Ohm's law, LED resistors, RC filters, 555 timers, PCB trace width - type a value and the answer appears as you type. No Calculate button, no sign-up.

Built for people who actually solder: hobbyists and makers, ham radio operators, electronics students, anyone wiring up a microcontroller board on a breadboard, and anyone whose desk has a multimeter on it. Every calculation runs on the device, so the app keeps working in a basement lab, out in the field, or on a plane.

WHAT YOU CAN WORK OUT

Circuits
- Ohm's law calculator - volts, amps, ohms and watts from any two values
- LED resistor calculator - supply, forward voltage and current in, series resistor out, snapped to the nearest E24 value you actually have in the drawer
- Voltage divider calculator, solved in both directions
- RC filter calculator - cutoff frequency, low-pass and high-pass
- 555 timer calculator - astable and monostable, with duty cycle
- Op-amp gain, inverting and non-inverting
- Zener diode regulator
- Series and parallel - equivalent resistance and equivalent capacitance
- Voltage drop over a long wire run
- Battery life from capacity and average current draw

PCB
- Trace width calculator - IPC-2221, by current and temperature rise
- Via current and barrel resistance
- Microstrip impedance with propagation delay

Converters
- Number base - hex, decimal, binary
- Temperature - Celsius, Fahrenheit, Kelvin
- AWG to mm² wire gauge
- dBm to watt

Look it up
- Resistor color code - an interactive 4, 5 and 6 band decoder
- SMD resistor code - 3-digit, 4-digit, R-notation and EIA-96
- Capacitor code - 104 is 100 nF, plus the tolerance letters
- SMD package sizes - 0402, 0603, 0805, imperial to metric

ON THE BENCH
- The math runs on the device - no connection needed to get an answer
- Free, paid for by ads. The ads need a connection, the calculators do not
- No account, no sign-up, nothing to register
- Search by name, synonym or abbreviation and start typing straight away
- Favorites and per-tool history, so last night's numbers are still there
- Every calculator shows its formula - check the math instead of trusting a black box

Whether you are sizing an LED resistor for a first breadboard build, decoding an SMD part you just desoldered, checking a trace width before the board goes out, or working out how long a coin cell will last, the calculator you need is one search away.

Made by an embedded engineer who got tired of installing five apps and opening a browser tab to bring up one board.