There are many single-board computers (SBCs) to choose from. Each has its own set of pros and cons, which makes it important to find the right one for your needs. If you’re after an SBC on a tight budget, look no further.

What Is a Single-Board Computer?

An SBC is a small computer that fits on a single circuit board. Note that a single-board computer differs from microcontrollers (such as the Arduino) as it’s a fully functional computer that can run an operating system.

SBCs are compact but usually quite powerful for their size. They can be used for a variety of applications, including as desktop computers, servers, and embedded systems. They are perfect for learning programming, robotics, and/or electronics.

The most popular SBCs by far are the Raspberry Pi computers. Due to their small size, they are often embedded in devices to maximize space without sacrificing functionality.

What Makes an SBC Cheap?

There are single-board computers of all shapes and sizes and for different budgets. In this article, we will be considering cheap single-board computers that fulfill the following criteria:

• Price: To be considered cheap, the SBC has to have a starting price less than $25.
• ARM-based: The processors in SBCs use different Instruction Set Architectures (or ISAs), including RISC-V, ARM, and x86. For ease of comparison, we will be considering only SBCs based on ARM processors here.
• Quad-core processor: A quad-core processor is a computer chip that has four cores. These cores work in parallel, allowing the processor to execute tasks faster. SBCs with quad-core processors are almost always faster than those with single cores. For example, the Raspberry Pi Zero 2 W is as much as five times faster than the original Raspberry Pi Zero. We will be focusing exclusively on SBCs with quad-core processors.

We will also take a look at the main features of these boards and their unique pros and cons.

1. Raspberry Pi Zero 2 W

The Raspberry Pi Zero 2 W is a perfect demonstration of how far computing has come in the last few years. This diminutive device packs a considerable amount of processing power in a 65 x 30 x 5mm form factor. The Zero 2 W is much faster than the previous Zero models due to its more powerful, quad-core processor and better specs overall, while still retaining the same size. Check out our Raspberry Pi Zero 2 W review.

Typical applications for the Raspberry Pi Zero 2 W include handheld gaming devices, motion detectors, security cameras, and for running small servers and ad blockers. It also features the same 40-pin GPIO expansion header found on other Raspberry Pi models.

The Raspberry Pi Zero 2 W features the RP3A0 system-in-package (SiP), containing an integrated CPU, GPU, and RAM. The processor is a quad-core 64-bit ARM Cortex-A53 clocked at 1GHz and the onboard GPU is a VideoCore IV. This SBC has up to 512MB SDRAM, a microSD card slot, a mini HDMI port, and a single micro USB OTG port. On board wireless connectivity includes Bluetooth 4.2, BLE, and 2.4GHz 802.11 b/g/n Wi-Fi.

The small form factor also makes it suited to embedded projects. However, it can be hard to find in stock at the official retail price. The 512MB of RAM also makes it unsuitable for most desktop applications. There is no onboard Ethernet, so if you need wired connectivity you’ll need to add an Ethernet/HUB HAT.

The Raspberry Pi Zero 2 W is available at the official price of just $15, which makes it the cheapest single-board computer on this list. If you don't need that much processing power, the original Raspberry Pi Zero is only $5, while the Zero W is $10.

2. Orange Pi Zero LTS

Made by Shenzhen Xunlong Software, the Orange Pi Zero is designed to compete with the original Raspberry Pi Zero. The LTS in the name stands for Long-Term Support, indicating that this model will be supported for longer than non-LTS versions. Also, the company claims that this variant is more power-efficient and thermal-efficient than the standard Orange Pi Zero.

Based on the powerful Allwinner H2 SoC, featuring a quad-core Cortex-A7 processor and Mali400 MP2 GPU, the Orange Pi Zero supports media playback of H.265/HEVC 1080p video. It features up to 256MB (standard) or 512MB SDRAM and has a microSD card slot, but only a 26-pin GPIO expansion header.

It is more powerful than the original Raspberry Pi Zero, but about equal to the Zero 2 W. On the plus side, it does include onboard Ethernet and can be found in stock easily. However, software support is limited and the device is more expensive than the Raspberry Pi Zero 2 W’s official price.

The Orange Pi Zero LTS is available for around $21 for the 512MB version, excluding shipping and tax. This makes it quite expensive for what you're getting. The Orange Pi Zero 2 is an upgraded version with better specs and is more reasonably priced at around $25.

3. Rock Pi S

Radxa is one of the major contenders in the single-board computer market. The Rock Pi S is a recent release from the company, aimed to compete with the Raspberry Pi Zero. The “S” in the name stands for small square, alluding to the shape of this tiny 43 x 43mm SBC.

The Rock Pi S is built around the Rockchip RK3308 SoC with a 64-bit, quad-core Cortex-A35 ARM processor. It offers both 256MB and 512MB RAM versions, and up to 8 gigabits (1GB) of onboard SD NAND in some variants. It also features a microSD card slot, 26-pin GPIO expansion header, USB 2.0 Type-A port, and one USB 3.0 Type-C port. Note that the 256MB version and some 512MB variants lack Wi-Fi, Bluetooth, PoE, and onboard storage.

A major advantage of this SBC is that it’s available with embedded storage. Also, it features a full-size USB 2.0 Type-A port and an Ethernet port. The downsides include limited software support, small onboard storage, and the absence of an HDMI port—instead, it's designed to work headlessly.

You can get the 512MB version of the Rock Pi S with Bluetooth and Wi-Fi for about $20.

4. Banana Pi BPI-M2 Magic

The Banana Pi BPI-M2 Magic is a compact and powerful quad-core SBC. Its Allwinner R16 SoC (as used in the Nintendo NES Classic) features four ARM Cortex-A7 CPU cores. Alternatively, this SBC can use the similar A33 SoC.

The BPI-M2 Magic includes 512MB of DDR3 SDRAM and onboard Wi-Fi and Bluetooth. It measures 51 x 51mm and weighs about 40g. There is an option provided for eMMC flash from 8GB up to 64GB, as well as a microSD card slot for storage. It also features a full 40-pin GPIO header with an identical pinout to Raspberry Pi boards.

Supported operating systems include Android, Debian, Ubuntu, Raspberry Pi OS, and several other lightweight Linux-based OSes. It offers two USB ports: an micro USB 2.0 OTG and an USB 2.0 Type-A port. There is no Ethernet port nor an HDMI output, but there is a MIPI DSI port to connect an LCD screen.

You can buy a Banana Pi BPI-M2 Magic with 8GB embedded storage for around $23.

5. NanoPi Neo LTS

The NanoPi Neo LTS is another Allwinner-based SBC designed to offer sufficient power and functionality at a reasonably low cost. It measures 40 x 40mm, even smaller than the Raspberry Pi Zero 2 W, and weighs 14g without pin headers. This makes it perfect for embedded applications.

This single-board computer costs $16 and is based on the Allwinner H3 SoC, with a quad-core Cortex-A7 clocked at up to 1.2GHz. There are two variants with 256MB and 512MB DDR3 RAM. It offers 10/100M Ethernet and includes a full-size USB Type-A port, a micro USB OTG port, and a 36-pin GPIO header.

On the downside, there is no onboard Bluetooth support or video output. Also, this board tends to run a bit hot, so you may need a heat sink. The NanoPi Neo LTS is available for around $16.

As Cheap As a Raspberry Pi

There are quite a number of low-cost single-board computers, but there is none that matches the affordability, functionality, and support offered by the Raspberry Pi Zero 2 W. At an official price of just $15, it's the cheapest single-board computer on this list and the perfect choice for low-cost electronics and IoT projects.