What Is pinout.xyz? The Raspberry Pi GPIO Pinout Reference

Updated

pinout.xyz is an interactive reference guide to the Raspberry Pi's 40-pin GPIO header and its interfaces. It is useful when you need to identify which physical pin carries which signal — for example, when wiring a sensor, checking whether a pin is safe for 3.3V logic, or confirming which pins support I2C, SPI, UART, or PWM before connecting a board.

What the site covers

The main page presents the standard 40-pin layout as an interactive diagram. Each pin is labeled with both its physical position and its function, so you can read the header in the same orientation as your board.

The pinout distinguishes several signal types:

Category Meaning
GPIO General Purpose IO — the configurable digital pins
SPI Serial Peripheral Interface
I2C Inter-integrated Circuit
UART Universal Asynchronous Receiver/Transmitter
PCM Pulse Code Modulation
Ground 0V reference pins
5v / 3.3v Power pins at each voltage

The legend also lists alternate function labels such as 1-WIRE, DPI, GPCLK, JTAG, PWM, SDIO, and WiringPi, which reflect the different modes a given GPIO can take.

Reading the header

The site's orientation guidance is: place your Pi with the GPIO header on the right and the HDMI port(s) on the left. From that view, the pins run in two rows of 20.

A few reference points from the documented layout:

  • Physical pin 1 — 3v3 Power
  • Physical pin 2 — 5v Power
  • Physical pin 6 — Ground
  • Physical pin 3 — GPIO 2 (I2C1 SDA)
  • Physical pin 5 — GPIO 3 (I2C1 SCL)
  • Physical pin 8 — GPIO 14 (UART0 TX)
  • Physical pin 10 — GPIO 15 (UART0 RX)
  • Physical pin 19 — GPIO 10 (SPI0 MOSI)
  • Physical pin 21 — GPIO 9 (SPI0 MISO)
  • Physical pin 23 — GPIO 11 (SPI0 SCLK)
  • Physical pin 24 — GPIO 8 (SPI0 CE0)
  • Physical pin 26 — GPIO 7 (SPI0 CE1)

The diagram can be mirrored to show the pinout as seen from the underside of the board, and rotated 180 degrees — useful when you are soldering or probing from the back.

Beyond the 40-pin header

The site is not limited to the main Raspberry Pi header. It also hosts:

  • Add-on board pinouts — hundreds of pinouts for Raspberry Pi HATs and pHATs, browsable through a board explorer.
  • Raspberry Pi Pico range — separate pinouts for the Pico, Pico W, Pico 2, and Pico 2 W.
  • Chip planners — for the RP2350A (QFN-60) and RP2350B (QFN-80).
  • Experimental pinouts — a minimal 40-pin Raspberry Pi pinout, plus Espressif ESP32 C5 DevKitC, ESP32 C3 DevKitC, and PJRC Teensy 4.0.

When to use it

Use pinout.xyz when you need a quick, visual answer to "which pin is this?" or "does this pin support I2C?" It is a reference, not a tutorial — it tells you what each pin does, not how to program it. For wiring a specific HAT, the board-specific pinout pages are the relevant section, since they map the add-on's connectors back to the Pi header.