Ohmica

Ohmica — The Electronics Calculator Your Multimeter Doesn't Have

Most electronics calculators give you a result.

Ohmica shows the result, the formula behind it, the substituted values, and the assumptions used.

Because when you're working on a real circuit, understanding the math matters.

Built for Arduino, ESP32, Raspberry Pi, makers, technicians, electronics hobbyists, and engineers, Ohmica helps you solve real-world electronics problems quickly and confidently.

WHY OHMICA

• Shows the actual formula used for every calculation • Displays substituted values for transparency • Supports engineering notation such as 4k7, 100nF, and 20mA • Works completely offline • No account required • No ads • Available in English and Vietnamese

Unlike generic calculators, Ohmica lets you verify the model behind the result.

For example, when calculating voltage drop, Ohmica can show:

Vdrop = 500 mA × 847 mΩ (AWG 14, Copper, 40 m Total Run)

You immediately know which assumptions were used and can validate the result with confidence.

CORE CALCULATORS

Fundamentals

• Ohm's Law • LED Resistor • Voltage Divider • Resistor Color Code

Passive Components

• Series / Parallel Resistance • Series / Parallel Capacitance • RC Time Constant • Capacitor Code • Inductor Code

Power & Wiring

• AWG Reference • Voltage Drop • Battery Runtime • PCB Trace Width • LED Strip Power

Digital & Control

• PWM & Frequency • I²C Pull-up Resistor • 555 Timer

REFERENCES

• ESP32 Pinout • Arduino Uno Pinout • Raspberry Pi GPIO • RJ45 T568A / T568B • Common I²C Addresses • SI Prefix Reference

Every tool is designed for practical electronics work rather than classroom exercises.

Whether you're designing an ESP32 project, sizing LED resistors, checking voltage drop, calculating RC timing, or selecting PCB trace widths, Ohmica helps you get answers without opening a browser or doing calculations by hand.

HISTORY & FAVORITES

• Save calculations for later • Restore previous inputs instantly • Favorites and recent tools • Search tools quickly • Keep frequently used tools within easy reach

OHMICA PRO

Unlock advanced professional tools with a one-time purchase.

Pro includes:

• E-Series Component Picker • Logic Levels • Voltage Regulator • Power Budget • UART Calculator • SPI Calculator • Transistor Switch Calculator • Export History • Future Pro tools

No subscription. No recurring fees. Pay once, use forever.

If Ohmica saves you time on the bench, Ohmica Pro helps support continued development while keeping the app independent and ad-free.

The calculator your multimeter doesn't have.