Scrypt: Litecoin's mining algorithm
GUIDE
Scrypt: Litecoin's mining algorithm
Scrypt is the hash function that secures Litecoin. Memory-hard design, originally intended to keep mining accessible. Here's how it works and what it means in 2026.
Scrypt is a proof-of-work hashing algorithm used by Litecoin and several other cryptocurrencies. Designed by Colin Percival in 2009 originally for password hashing, scrypt was adapted for cryptocurrency mining by Charlie Lee when he created Litecoin in 2011. The defining property: scrypt is memory-hard — it requires significant RAM per computation, making specialized ASIC hardware more expensive to build than SHA-256 ASICs (Bitcoin's algorithm). This property was intended to keep mining more decentralized among GPU miners; in practice, scrypt ASICs eventually emerged and now dominate Litecoin mining.
What 'memory-hard' means
A normal hash function (like SHA-256) uses very little memory per computation — just the input data and a small working set. ASICs for SHA-256 can be built with minimal on-chip memory, making them cheap relative to their computational output. Scrypt was designed to require a large working memory buffer per hash computation. To compute a scrypt hash, you fill a buffer with pseudo-random data and then access the buffer in a pattern that depends on the input. This forces the hasher to have fast access to a substantial chunk of RAM. For ASIC designers, adding RAM is expensive — both the silicon area and the power cost. In theory, this makes the ASIC advantage over commodity CPU/GPU hardware smaller. In practice, the advantage is still significant but less extreme than SHA-256's CPU-to-ASIC gap.
Scrypt vs SHA-256
| Feature | Property | Scrypt (Litecoin) | SHA-256 (Bitcoin) |
|---|---|---|---|
| Memory requirement per hash | Significant (128+ KB typical) | Minimal | |
| ASIC-friendliness | Lower (RAM adds cost) | High | |
| Current mining hardware | Scrypt ASICs (Antminer L7, L9, others) | SHA-256 ASICs (Antminer S-series, others) | |
| Historically GPU-profitable | Yes, until ~2014 | Yes, until ~2012 | |
| Power draw typical modern ASIC | 3-3.5 kW (L9 class) | 3-4 kW (S21 class) | |
| Hash rate basis | Mh/s or Gh/s | Th/s or Ph/s | |
| Widely-known cryptocurrency | Litecoin, Dogecoin (merge-mined) | Bitcoin, Bitcoin Cash |
Memory requirement per hash
ASIC-friendliness
Current mining hardware
Historically GPU-profitable
Power draw typical modern ASIC
Hash rate basis
Widely-known cryptocurrency
Mining scrypt today
In 2026, profitable Litecoin mining requires scrypt ASICs. The Antminer L7 and L9 (or equivalent from other manufacturers) are the standard. Hash rates are typically measured in Gh/s (gigahashes per second) per machine. A modern miner draws 3-3.5 kW; electricity cost is the dominant operating expense. GPU and CPU mining are no longer economically viable — your hash rate is vanishingly small relative to ASIC-equipped miners, and you'll spend more on electricity than you earn. The merge-mined relationship with Dogecoin is worth noting: Litecoin miners can simultaneously secure Dogecoin (which uses the same scrypt algorithm), earning DOGE block rewards on top of LTC rewards without extra energy. Merge mining has boosted miner profitability since AuxPoW activation in 2014 and is one reason Litecoin's hash rate remains well-supported.