ESP32 vs Arduino UNO: which board should you build with?
The Arduino UNO R3 is the board most tutorials assume: 5 V logic, a socketed ATmega328P and no surprises. The ESP32 is far more chip for the money — 32-bit cores at up to 240 MHz, Wi-Fi and Bluetooth on the die, and hundreds of times the RAM. This page compares them on the manufacturers’ own specifications so the choice follows your project.
Specifications
| Specification | ESP32 | Arduino UNO R3 |
|---|---|---|
| MCU | Xtensa LX6, 32-bit | Microchip ATmega328P, 8-bit AVR |
| Cores / clock | Dual-core, up to 240 MHz | Single-core, 16 MHz |
| RAM / flash | 520 KB SRAM and 448 KB ROM on the chip; firmware lives in external flash, typically 4 MB on modules | 2 KB SRAM, 1 KB EEPROM, 32 KB flash (0.5 KB reserved for the bootloader) |
| Radios | Wi-Fi 802.11 b/g/n (2.4 GHz), Bluetooth 4.2 BR/EDR and Bluetooth LE | None |
| Voltage | 2.3–3.6 V; Espressif recommends a 3.3 V supply able to deliver 500 mA or more | 5 V logic; 7–12 V into the power jack recommended (6–20 V limit) |
| Typical power | Deep-sleep 10 µA (RTC timer and memory retained), light-sleep 0.8 mA; Wi-Fi transmit is the heavy, spiky part | No low-power modes or sleep currents are published: the board draws operating current whenever it is powered |
| Price class | Budget. Dev-board prices vary by vendor; there is no single official price | Mid. About $29 from Arduino’s official store |
Figures are typical values from the linked sources, not guarantees. Prices are the manufacturers’ published prices where they publish one; resellers vary.
How to choose
Choose the ESP32 when…
- The project goes on a network: Wi-Fi and Bluetooth are on the chip, with mature libraries around them.
- It must run for months on a battery: the ESP32 documents a 10 µA deep-sleep, while the UNO has no comparable mode.
- It needs headroom — buffers, TLS, audio or a display — where 520 KB SRAM and 32-bit cores earn their keep.
Choose the Arduino UNO when…
- The lesson, shield or classroom you are building on assumes an UNO and 5 V parts.
- You want the microcontroller socketed and replaceable when a pin dies — the UNO R3 ships the ATmega328P that way.
- Simplicity beats capability: 32 KB of flash keeps programs small enough to read end to end.
Where to go next
A 3D-Printed Planter That Monitors Indoor CO₂
Behind its geometric planter shell, murCO uses an ESP32-based controller and SCD40 sensor to send local CO₂, temperature, and humidity readings to Home Assistant. LEDs, optional speech, and Bluetooth proxy features make ventilation information useful without depending on a dashboard. The open-source repository and project documentation provide implementation details.
Read the build on openelab.io: A 3D-Printed Planter That Monitors Indoor CO₂Build an ESP32 Sparkle Motion Light
Tiny points of colored light can feel surprisingly alive when they move, fade, and sparkle independently. This project pairs an ESP32-based Adafruit board with addressable LEDs and CircuitPython, giving makers a hands-on way to build an animated display, then adjust its colors, timing, brightness, and physical form.
Read the build on cdn-learn.adafruit.com: Build an ESP32 Sparkle Motion LightReliable ESP-NOW RC Car With ESP32 and ESP8266
At 2.02 volts, a battery pack exposed the gap between firmware’s “protected” message and real electrical safety. This ESP-NOW RC car pairs an ESP32 controller with an ESP8266 vehicle board, then adds packet checks, acknowledgements, failsafes, pairing, and hard-won debugging lessons from actual hardware faults.
Read the build on learniot.in: Reliable ESP-NOW RC Car With ESP32 and ESP8266Build an ESP32 MAX30102 Vital Signs Sensor
Three useful readings come from one fingertip module: heart rate, SpO2, and temperature. This ESP32 project covers the wiring, Arduino sketches, and optical sensing behind each value. It is a practical introduction to I2C and physiological data, but the results are experimental and not suitable for medical diagnosis.
Read the build on randomnerdtutorials.com: Build an ESP32 MAX30102 Vital Signs SensorReplace a RIKA Stove Dongle with ESP32-S3
RIKA pellet stoves normally send data through a proprietary Firenet 2.0 dongle and cloud service. Open Firenet substitutes an ESP32-S3, speaking the stove’s USB protocol while providing Wi-Fi, a local control page, and a REST API. Careful board selection matters, and this unofficial appliance interface carries real installation risks.
Read the build on github.com: Replace a RIKA Stove Dongle with ESP32-S3Turn a Sonoff NSPanel into Local Control
The Sonoff NSPanel EU can do more than control eWeLink devices. With ESPHome on its ESP32 and Home Assistant as the local controller, its touchscreen, buttons, relays, and temperature sensor become useful across a wider home system. Flashing takes care, and the 240 V terminals require serious electrical safety.
Read the build on jirkovynavody.cz: Turn a Sonoff NSPanel into Local Control