4.14[Blockchain Technology](https://wealtii.com/learn) # Layer 1 vs Layer 2 Blockchains: What's the Difference? By [Zayd Ahmed](https://wealtii.com/editorial-policy#zayd-ahmed), Founder & CEO, Wealtii · Published 11 August 2026 · Last reviewed 21 October 2026 A **Layer 1** blockchain is a base network, such as Bitcoin, Ethereum or BNB Smart Chain, that runs its own consensus and settles its own transactions. A **Layer 2** is a separate network built on top of a Layer 1: it executes transactions elsewhere and posts data or proofs back, borrowing much of the base layer's security. ## What is a Layer 1 blockchain? A Layer 1 has its own validators or miners, its own [consensus mechanism](https://wealtii.com/learn/blockchain-consensus-mechanisms) and usually its own native coin to pay fees. It is the final source of truth: once a transaction is final on Layer 1, nothing built on top can override it. Bitcoin, Ethereum, Solana and BNB Smart Chain are all Layer 1 networks. They differ in how they balance the [blockchain scalability trilemma](https://wealtii.com/learn/blockchain-scalability-trilemma): Bitcoin and Ethereum keep their base layers modest so that ordinary computers can verify them, while faster chains accept smaller validator sets. ## What is a Layer 2 and how does it work? A Layer 2 processes transactions outside the base chain, then uses the base chain to store data and settle disputes. Ethereum.org's working test is whether a network stores its data on Ethereum mainnet; projects that do are usually called rollups. ### Optimistic rollups Optimistic rollups, such as Base (built with the OP Stack), assume each batch of transactions is valid and let anyone challenge it with a fraud proof. Withdrawals back to Ethereum wait for a challenge period of roughly seven days. ### Zero-knowledge (ZK) rollups ZK-rollups, such as Starknet, publish a validity proof with each batch, so Ethereum can check the result mathematically. Withdrawals do not need a week-long challenge window, but generating the proofs takes heavy computation. ### Payment channels Payment channels, such as Bitcoin's Lightning Network proposed in 2016, let two parties transact many times off-chain and record only the opening and closing balances on Layer 1. ### Sidechains are not Layer 2s Sidechains run their own consensus and do not post their state back to Ethereum, so ethereum.org notes that they "do not inherit Ethereum's security properties." For a closer look at each design, see [types of layer 2 solutions](https://wealtii.com/learn/layer-2-solutions-explained). ## Layer 1 vs Layer 2: how do they compare? | Factor | Layer 1 | Layer 2 (rollup) | | --- | --- | --- | | Security comes from | Its own validators or miners | Mostly the Layer 1 it posts data to, plus its own operators | | Typical fees | Higher when the base layer is busy | Usually lower. Ethereum.org's Layer 2 page showed average costs of about $0.019 on Ethereum and $0.0016 on Ethereum-based networks (accessed 21 Oct 2026) | | Finality | Set by its own consensus (about 15 minutes on Ethereum) | Fast confirmations from the sequencer; full finality once its data is final on Layer 1 | | Moving funds to Layer 1 | Not applicable | About seven days from optimistic rollups; faster from ZK-rollups | | Main extra risks | Consensus attacks and client bugs | Centralised sequencers, upgradeable contracts and bridge bugs | | Examples | Bitcoin, Ethereum, Solana, BNB Smart Chain | Arbitrum, Optimism, Base and Starknet on Ethereum; Lightning on Bitcoin | ## Did Dencun and later upgrades make Layer 2s cheaper? Yes, that was their purpose. Before March 2024, rollups posted their data as calldata, which ethereum.org describes as expensive because every node processes it and it lives on-chain forever. The [Dencun upgrade](https://ethereum.org/en/history/) on 13 March 2024 added blobs (EIP-4844): temporary data attached to blocks and deleted after about 18 days. Pectra (7 May 2025) raised the blob target from three to six per block, and Fusaka (3 December 2025) introduced PeerDAS, so nodes store only a fraction of blob data, along with "blob-parameter-only" forks that can raise capacity between major upgrades. ## What are the risks of using a Layer 2? - **Sequencer control:** many rollups use a single sequencer, which ethereum.org notes has "greater control over the ordering of transactions." If it goes offline, the network can stall. - **Upgrade keys:** teams can often change rollup contracts. Check whether there is a delay that lets users exit first; [L2BEAT's stages framework](https://l2beat.com/stages) rates each network. - **Bridges:** moving assets between layers relies on bridge contracts, and bridges have been behind some of the largest hacks in crypto. - **Fragmentation:** funds on one Layer 2 are not automatically usable on another, and moving them adds cost and delay. ## Is BNB Smart Chain a Layer 1 or a Layer 2? BNB Smart Chain is a Layer 1 with its own Proof of Staked Authority validator set, not a rollup on Ethereum. It targets 0.45-second blocks and usually finalises within two blocks. Because it runs the same virtual machine as Ethereum (see [what EVM compatibility means](https://wealtii.com/learn/ethereum-virtual-machine-evm)), the same wallets and address formats work on both, but tokens on BNB Smart Chain are separate from tokens on Ethereum. **Which layer Wealtii uses:** Wealtii's funds and USDT deposits use BNB Smart Chain directly (BEP-20 tokens), not a Layer 2. Network gas fees there are typically under $0.50. Read [what BNB Smart Chain is and how it works](https://wealtii.com/learn/what-is-bnb-chain) for background. ## Frequently Asked Questions ### What is the difference between Layer 1 and Layer 2? A Layer 1 is a base blockchain with its own consensus and final settlement, such as Ethereum. A Layer 2 runs on top of a Layer 1, executes transactions off the main chain and posts data or proofs back to it for security. ### Is Ethereum a Layer 1 or a Layer 2? Ethereum is a Layer 1. Networks such as Arbitrum, Optimism, Base and Starknet are Layer 2 rollups that post their data to Ethereum. ### Are Layer 2 networks as secure as Layer 1? Not fully. Rollups inherit much of their security from the Layer 1 they post data to, but they add risks of their own, such as a single sequencer, upgradeable contracts and bridge bugs. Maturity varies widely between networks. ### Why do withdrawals from some Layer 2s take seven days? Optimistic rollups assume transactions are valid unless someone proves fraud, so withdrawals to Ethereum wait for a challenge period of roughly seven days. ZK-rollups use validity proofs and do not need that waiting period. ## Sources & References 1. [ethereum.org — Layer 2 networks](https://ethereum.org/en/layer-2/) (accessed 21 Oct 2026) 2. [ethereum.org — Optimistic rollups](https://ethereum.org/en/developers/docs/scaling/optimistic-rollups/) (accessed 21 Oct 2026) 3. [ethereum.org — Sidechains](https://ethereum.org/en/developers/docs/scaling/sidechains/) (accessed 21 Oct 2026) 4. [ethereum.org — Danksharding and proto-danksharding (EIP-4844)](https://ethereum.org/en/roadmap/danksharding/) (accessed 21 Oct 2026) 5. [Poon, J. and Dryja, T. (2016) — The Bitcoin Lightning Network](https://lightning.network/lightning-network-paper.pdf) (accessed 21 Oct 2026) Disclaimer: This content is for educational purposes only and does not constitute financial, tax, or legal advice. Digital assets are volatile and carry risk of loss. Wealtii is early-stage and is not regulated by any financial authority. ## Further reading from official sources - [NIST: Blockchain Technology Overview](https://csrc.nist.gov/pubs/ir/8202/final) - [Bitcoin white paper](https://bitcoin.org/bitcoin.pdf) [Zayd Ahmed](https://wealtii.com/editorial-policy#zayd-ahmed) Founder & CEO, Wealtii Computer Science Engineer | 5+ Years in DeFi & Digital Assets