A developer has built a fully self-powered computer that matches the exact physical dimensions of a standard credit card [1].

The project demonstrates the extreme limits of hardware miniaturization, proving that a functional computer with its own power source can fit within a standard wallet slot. This achievement pushes the boundaries of portable computing and ultra-thin electronics.

Krauseler, a Reddit user and GitHub developer, announced the project in early May on the r/electronics forum [1]. The device adheres to the ISO/IEC 7810 ID-1 standard, measuring 85.6 mm by 53.98 mm [2]. To achieve this form factor, the computer is only about 1 mm thick [3].

To manage power and visibility within such a slim profile, Krauseler integrated an e-ink screen [3]. This display technology allows for low-power output, which is essential for a device that is fully self-powered [1].

Engineering a device of this scale presented significant challenges. The creator said that the strict adherence to the credit card thickness was a primary obstacle during development.

"Going just 0.5 mm thicker would probably have saved me months of engineering," Krauseler said [4].

Despite the difficulty, the developer successfully integrated the processor, power supply, and display into the thin chassis. The source code for the project has been shared on GitHub to allow other developers to study the architecture [1].

"I built a fully self-powered computer that actually fits the ISO/IEC 7810 ID-1 credit-card dimensions," Krauseler said [2].

The device represents a departure from common hobbyist boards like the Raspberry Pi, which are significantly larger than the 1 mm thickness of this build [5]. By prioritizing the ID-1 dimension, the developer focused on a specific geometric constraint rather than raw processing power.

“The device is only about 1 mm thick and includes an e-ink screen for low-power output.”

This project highlights a trend in 'extreme miniaturization' where the goal is not necessarily commercial utility, but the exploration of physical limits. By utilizing e-ink and self-contained power in a 1 mm frame, the build provides a blueprint for future wearable or embedded tech that must operate without external power or bulky casings.