Ethash is the name of the PoW algorithm used in Ethereum.
Originally, this was proposed as the Dagger- Hashimoto algorithm, but much has changed since the first implementation, and the PoW algorithm has now evolved into what’s known as Ethash now.
A Complete Guide to Understanding This Blockchain Concept
Similar to Bitcoin, the core idea behind mining is to find a nonce (a random arbitrary number) which once concatenated with the block header and hashed, results in a number that is lower than the current network difficulty level.
Initially, the difficulty was low when Ethereum was new, and even CPU and single GPU mining was profitable to a certain extent, but that is no longer the case.
Now either pooled mining is profitable, or large GPU mining farms are used for mining purposes.
Ethash is a memory-hard algorithm, which makes it difficult to be implemented on specialized hardware.
As in Bitcoin, ASICs have been developed, which have resulted in mining centralization over the years, but memory- hard PoW algorithms are one way of thwarting this threat, and Ethereum implements Ethash to discourage ASIC development for mining.
Ethash is a memory hard algorithm and developing ASICs with large and fast memories is not feasible.
Why This Matters for Blockchain Technology
This algorithm requires choosing subsets of a fixed resource called Directed Acyclic Graph (DAG) depending on the nonce and block headers.
Mining can only start when DAG is completely generated the first time a mining node starts.
The time between every 30,000 blocks is around 5.2 days and is called epoch.
This DAG is used as a seed by the PoW algorithm called Ethash.
Key Points to Remember
- Ethash Ethash is the name of the PoW algorithm used in Ethereum.
- Originally, this was proposed as the Dagger- Hashimoto algorithm, but much has changed since the first implementation, and the PoW algorithm has now evolved into what’s known as Ethash now.
- Similar to Bitcoin, the core idea behind mining is to find a nonce (a random arbitrary number) which once concatenated with the block header and hashed, results in a number that is lower than the current network difficulty level.
- Initially, the difficulty was low when Ethereum was new, and even CPU and single GPU mining was profitable to a certain extent, but that is no longer the case.
Going Deeper: Advanced Concepts
According to current specifications, the epoch time is defined as 30,000 blocks.
The current reward scheme is 3 Ethers for successfully finding a valid nonce.
In addition to receiving 3 Ethers, the successful miner also receives the cost of the gas consumed within the block and an additional reward for including stale blocks (uncles) in the block.
A maximum of two uncles are allowed per block and are rewarded 7/8 of the normal block reward.
Conclusion
Ethash represents one of the many innovative layers that make blockchain technology so powerful and transformative. As distributed systems continue to evolve, a solid understanding of these core concepts becomes increasingly valuable — not just for developers, but for anyone building, investing in, or working alongside blockchain-powered systems.
Whether you are just starting your blockchain journey or deepening existing expertise, mastering these fundamentals gives you the tools to think clearly about decentralized systems and make smarter decisions in this rapidly evolving space.