Raspberry Pi · Single-board computer

Raspberry Pi 26-pin GPIO Header

The original Model A and Model B header. Pins 1 to 26 match the 40-pin layout, with three that moved between board revisions.

1.Pinout diagram

Odd pins

RPI 26-PIN

Even pins

Pin detail

Hover a pin for its mappings and gotchas. Click to keep it here.

Fig. 1. Raspberry Pi 26-pin GPIO Header, 2x13 2.54 mm (P1). Hover or tap a signal to light up every pin that carries it.

Pins 1 to 26 of the 40-pin header are electrically the same, so a 26-pin HAT or cape works on a modern Pi. The reverse is not true.
Rev 1 boards (the first Model B, 256 MB) use GPIO0, GPIO1 and GPIO21 where rev 2 and later use GPIO2, GPIO3 and GPIO27. Rev 1 also puts the I2C pins on bus 0 instead of bus 1, so `i2cdetect -y 0` on an old board and `-y 1` on everything since.
Rev 2 boards add a second 8-pin header, P5, that is not on this diagram. It carries GPIO28 to GPIO31 and is unpopulated from the factory.
3.3 V only, like every Pi. A 5 V output into any of these damages the SoC.
GPIO2 and GPIO3 carry fixed 1.8 kOhm pull-ups to 3V3 on the board.

Every pin, alias and mapping. This is the table that prints.

Table 1. Pin assignments.

Complete pin reference for Raspberry Pi 26-pin GPIO Header
Pin	Name	Also called	Functions	Notes
1	3V33.3 V	-	3.3 V supply out	~50 mA budget shared with pin 17.
2	5V5 V	-	5 V supply out	Fed straight from the USB-C / micro-USB input, upstream of the 3V3 regulator.
3	GPIO2I²C	BCM 2, SDA1, I2C1 SDA, Rev 1: GPIO0	I2C1 SDA	Fixed 1.8 kΩ pull-up to 3V3. Rev 1 boards have GPIO0 here, on I2C0 rather than I2C1.
4	5V5 V	-	5 V supply out
5	GPIO3I²C	BCM 3, SCL1, I2C1 SCL, Rev 1: GPIO1	I2C1 SCL	Fixed 1.8 kΩ pull-up to 3V3. Also wakes the Pi from halt when pulled low. Rev 1 boards have GPIO1 here, on I2C0 rather than I2C1.
6	GND	-	Ground
7	GPIO4Clock	BCM 4, GPCLK0	GPCLK0	Default 1-Wire bus pin (w1-gpio overlay), used by DS18B20 sensors.
8	GPIO14UART	BCM 14, TXD0, TXD	UART0 TXD
9	GND	-	Ground
10	GPIO15UART	BCM 15, RXD0, RXD	UART0 RXD
11	GPIO17	BCM 17	SPI1 CE1
12	GPIO18PWMClock	BCM 18, PCM_CLK	PWM0, PCM/I2S CLK, SPI1 CE0	The pin WS2812/NeoPixel libraries use, because it reaches PWM0 via DMA.
13	GPIO27	BCM 27, Rev 1: GPIO21	SD1 DAT3	Rev 1 boards have GPIO21 here. This is the pin that catches people reusing old code.
14	GND	-	Ground
15	GPIO22	BCM 22	SD1 CLK
16	GPIO23	BCM 23	SD1 CMD
17	3V33.3 V	-	3.3 V supply out
18	GPIO24	BCM 24	SD1 DAT0
19	GPIO10SPI	BCM 10, MOSI	SPI0 MOSI
20	GND	-	Ground
21	GPIO9SPI	BCM 9, MISO	SPI0 MISO
22	GPIO25	BCM 25	SD1 DAT1
23	GPIO11SPIClock	BCM 11, SCLK	SPI0 SCLK
24	GPIO8SPI	BCM 8, CE0	SPI0 CE0
25	GND	-	Ground
26	GPIO7SPI	BCM 7, CE1	SPI0 CE1

Found a wrong pin? The whole board is one file, data/boards/raspberry-pi-26-pin.json.