Electronics Calculators

Battery Life Calculator

Estimate runtime for any battery-powered project. Enter battery capacity (mAh) and average current draw to get hours of runtime. Includes efficiency factor for real-world derating.

Capacitor Calculator

Calculate capacitive reactance (Xc) at a given frequency, the energy stored in a capacitor, and the charge/discharge time constants. Covers decoupling, filter, and energy storage applications.

Inductor Calculator

Calculate inductive reactance (XL) at any frequency, energy stored in an inductor, and the resonant frequency of an LC circuit. Useful for RF chokes, power supply filtering, and LC tank circuits.

LED Resistor Calculator

Calculate the correct series resistor for any LED circuit. Enter your supply voltage, LED forward voltage, and desired current — get the exact resistance, nearest E12 standard value, and power rating.

Ohm's Law Calculator

Solve for any unknown in Ohm's Law — voltage, current, or resistance — by entering the other two. Also calculates power dissipation so you can pick the right resistor wattage rating.

Power Calculator

Calculate electrical power in watts from voltage and current, or find any one unknown when the other two are known. Covers DC circuits, resistive loads, and component power budgets.

Pull-up Resistor Calculator

Find the ideal pull-up or pull-down resistor for I2C buses, open-drain GPIO lines, and switch inputs. Balances rise time against power consumption for your supply voltage and bus speed.

RC Time Constant Calculator

Resistor Color Code Calculator

Voltage Divider Calculator

Instantly calculate the output voltage of any resistor voltage divider. Useful for level-shifting 5V signals to 3.3V for ESP32/ESP8266 inputs, biasing op-amps, and ADC reference networks.

ADC Resolution Calculator

Calculate ADC voltage resolution (LSB size), the number of steps, and the voltage at any digital reading. Covers Arduino Uno (10-bit), ESP32 (12-bit), STM32 (12-bit), and Raspberry Pi ADC hats.

ESP32 Flash Size Calculator

Visualise how the ESP32 flash is split across the bootloader, partition table, NVS, OTA, SPIFFS/LittleFS, and app partitions. Helps you choose the right partition scheme for your firmware size.

I2C Pull-up Calculator

Calculate the minimum and maximum pull-up resistor values for I2C bus speeds of 100 kHz (Standard), 400 kHz (Fast), and 1 MHz (Fast-Plus). Prevents signal integrity issues caused by too-weak or too-strong pull-ups.

PWM Duty Cycle Calculator

Calculate PWM frequency, period, duty cycle percentage, and on/off times. Works for Arduino analogWrite (8-bit), ESP32 LEDC (up to 16-bit), and servo pulse width calculations.

UART Baud Rate Calculator

Calculate UART frame duration, bytes per second throughput, and baud rate error percentage for common MCU clock speeds. Helps you pick the closest standard baud rate with acceptable error.

Battery Runtime Calculator

Calculate battery runtime for IoT devices with sleep/wake cycles. Enter active current, sleep current, duty cycle, and battery capacity to get realistic runtime estimates for ESP32 deep sleep projects.

LoRa Airtime Calculator

Calculate LoRa packet time on air from spreading factor, bandwidth, coding rate, and payload length. Also shows duty cycle compliance for EU 868 MHz (1%) and US 915 MHz regulations.

MQTT Payload Size Calculator

Estimate total MQTT packet size including fixed header, variable header, topic length, and QoS overhead. Useful for staying within broker limits and optimising bandwidth on constrained devices.

Wi-Fi Range Estimator

Estimate the practical Wi-Fi range of your ESP32, ESP8266, or other 2.4 GHz module based on transmit power, antenna gain, and environment. Uses the Friis transmission equation with indoor loss factors.

ASCII Converter

Look up any ASCII character by its decimal code, hex value, or binary representation. Useful when working with serial communication, UART debugging, and string encoding in embedded firmware.

Binary ↔ Decimal ↔ Hex Converter

Instantly convert any number between binary (base 2), decimal (base 10), hexadecimal (base 16), and octal (base 8). Type in any field and all others update live. Essential for working with registers, masks, and memory addresses.

Data Size Converter

Convert between bits, bytes, kilobytes, megabytes, and gigabytes using both decimal (SI) and binary (IEC) definitions. Useful for flash sizing, SD card capacity planning, and network bandwidth calculations.

Unit Converter

Convert between common units used in electronics and making — length (mm/cm/inch), weight (g/kg/oz), temperature (°C/°F/K), and electrical units (mV/V, mA/A, mΩ/kΩ/MΩ).