## Definition

FPGA mining is cryptocurrency mining done with field-programmable gate arrays, chips that can be configured after manufacturing to act like custom digital circuits. In [Bitcoin's early mining history](https://en.bitcoin.it/wiki/Mining_hardware_comparison), FPGAs filled the gap between GPU mining and purpose-built ASIC miners. They were much more power efficient than graphics cards for SHA-256 hashing, while still being reprogrammable for different designs.

## How It Works

Bitcoin mining requires hardware to repeatedly hash [block header data](https://developer.bitcoin.org/reference/block_chain.html#block-headers) with SHA-256 until it finds a result below the network target. An FPGA miner loads a hardware design, often called a bitstream, that arranges the chip's logic blocks into a SHA-256 hashing pipeline. Instead of running the algorithm as ordinary software, the FPGA performs the work as a dedicated circuit.

In practice, the miner receives work from mining software or a pool, changes nonce values and other fields, and reports valid shares or blocks when it finds them. Operators can tune clock speed, voltage, cooling, and firmware, so FPGAs rewarded careful engineering. They also required more technical skill than ordinary PCs and were eventually outclassed by ASIC miners, whose chips are fixed for one algorithm but deliver far higher hash rate per watt.

## Why It Matters

FPGA mining matters because it shows how Bitcoin mining moved from general computers toward specialized industrial hardware. The progression from CPUs to GPUs, then FPGAs, then ASICs made clear that profitability depends on energy efficiency, hardware cost, cooling, and operational skill, not just access to a machine that can calculate hashes.

The technology also explains a core tradeoff in mining hardware. FPGAs are flexible and can be reprogrammed for experiments, alternative proof-of-work algorithms, or non-mining workloads. ASICs are less flexible but far more efficient for [Bitcoin's SHA-256 workload](https://learnmeabitcoin.com/technical/mining/sha-256/). Because Bitcoin's total hash rate is so large, that efficiency advantage pushed FPGA mining out of normal Bitcoin competition.

## Related Terms

FPGA mining is closely related to proof of work, hash rate, ASIC miners, and mining difficulty. Proof of work defines the competitive process, hash rate measures how many attempts hardware can make, and difficulty adjusts how hard it is to find a valid block. ASIC mining is the later hardware stage that made FPGAs mostly historical for Bitcoin.

- [Proof of Work](/glossary/proof-of-work)
- [Hash Rate](/glossary/hash-rate)
- [ASIC Miner](/glossary/asic-miner)
- [Mining Difficulty](/glossary/mining-difficulty)